Federico's Early Deaths (?)
[Front-paged. stabguy]
So here's my messing around with Federico. I knew the moving exploit already from Aurel's vids (http://www.youtube.com/watch?v=6huczmD4lLE in the beginning) and so I figured, why not try to kill Federico? It took me over an hour to get Federico to that spot, but the end result was worth it.
You can still start the mission by going back to the spot Federico originally stood and pressing Y to talk. Weird quirk in the programming, since Aurel's superfast blitzes showed talking to the mercenaries on the spot where they stood after they'd been moving. However, since you're teleported to Federico, you get stuck in Limbo and can't move on. Quitting to the main menu and returning fixes this and gets Federico to run from his original location. During this time, it's also possible to get him to die, I think, but I haven't researched it yet. Because you can move him around, it's also possible to blitz this memory, going from the talking scene to the doctor's scene immediately.
Next up is the race. Turns out the good ol' obstruction charm from AC1 (Ian's turkey shoot vids) still works! My execution here is very sloppy, but I had already tried over 20 times or something 
It's possible to block Federico from coming up to the roof every single time (if he does come up, I just knock him of using the high-profile grab move), in which case you'll only need to block him four times.
When he takes the alternative route, you have to grapple him, otherwise he'll reach the marker and you'll lose the race. Once he's done running, there are no waypoints for him, so this is akin waypoint separation, rendering Federico standing still. I think the comments Ezio makes when I push Federico from the roof are hilarious.
I move Federico around by a combination of punching and high-profile grabbing, mostly the latter, since it's easier to aim. It turns out he teleports towards you, and then disappears altogether. The 'one opponent has abandoned the race' is intriguing. We have never seen a race between more than one opponent, have we? Or have we ever even raced against another opponent (except for this one)? No, only against the clock. So why is it possible for non-existing opponents to abandon a race? The current race isn't meant to be this way. Federico will always hit the waypoint if you don't block him from doing so. So why put such a message in?
Also funny I could synchronize the viewpoint. Had to do it again in the following memory, though.
Another opportunity to kill Federico presents itself in the memory "Paperboy", where he waits for you at the Auditore home after you've delivered the letter to Lorenzo. I figured it took way too long to show this complete for a rather meagre reward, so I decided not to.
Hope you enjoyed the video!
Really good job, it's a shame he reappears for the scene. This just shows that there is still more stuff to find in the older games. 
I knew the moving exploit already from Aurel's vids.
The video with the dummies wasn't really good with showing the exploit. A better example is There is no Dante and Silvio.
It took me over an hour to get Federico to that spot, but the end result was worth it.
Wow, it took that long? I remember when I moved the mercenaries I kept track of the time for moving some of them, which was less than twenty minutes each about. For two of those three mercenaries I had to move them more than once to get in the right spot for the blitz. 
It may be faster if you move the grabbed characters around in a full circle.
You can still start the mission by going back to the spot Federico originally stood and pressing Y to talk. Weird quirk in the programming, since Aurel's superfast blitzes showed talking to the mercenaries on the spot where they stood after they'd been moving.
Locking on to the mercenaries is what allows me to talk to them. At the beginning of the video I walk towards the mercenary and try to interact, but it didn't have the option (this was my first time moving them). Then I locked on and the option appeared. 
Wow, I can't even tell you how much I enjoyed that. 
Yeah it took that long. It's quite an end and I wasn't so good at moving Federico around.
I'll update the OP with the other vid.
Glad you enjoyed the video, Lisa.
Turns out the good ol' obstruction charm from AC1 (Ian's turkey shoot vids) still works! My execution here is very sloppy, but I had already tried over 20 times or something
When he takes the alternative route, you have to grapple him, otherwise he'll reach the marker and you'll lose the race.
I've been trying to replicate this. The part that isn't working for me is this last step when Federico takes the alternative route. First of all, "grapple" = "high-profile grab", right? Even when I successfully grab him, Federico recovers and runs into the tornado of light to win the race. Have you done this more than once, Phi?
Because I'm better at blocking than grappling, I've explored that strategy further. First I block Federico four times as shown in the video. When he takes the alternate route I block him again, either at the summit of the roof or on the railing he jumps from. This block causes Federico to fall to the street, which is non-fatal. He runs around to the north side of the church to try a completely different route.
Now this is where it gets interesting. Federico usually flails around for a moment and ends up floating about a foot off the ground with his arms over his head, as if jumping to block a basketball shot. There's a trick to getting him unstuck from this position: pause the game (but do not exit) and resume. Federico wakes up and proceeds to the ladder opposite the north side of the church. If left unobstructed he wins the race. My next step will be to block him on the ladder.
If any of this is unclear I can put together a demo video. My goal is to get the "one opponent has abandoned the race" message. For that I would welcome assistance.
I'm pretty sure I got him immobilized a couple times, but it's been 6 years, so yeah. In the text I mention the grapple once he gets up on the roof as paramount, so there's that.
As far as "opponent abandoned the race" goes, I only got that once. It's either despawning- or time-related.