Alioune noted that this isn't Magneto/Doctor Doom specific, and more will be coming on both his YouTube and ELive channels in the future.
Also, there's a Magneto/Doom combo video that was posted a few weeks back by Alioune, which is below.
If you want to go further, there's an ELive cast of this video available giving a further breakdown of what's going on.
This works for any character with any multi hitting assist. Within the first week MvC3 came out i was practicing with Captain America, just happen to throw out an assist the moment i grab and the cpu is getting hit while the grab animation is starting which was pretty cool. Glad to finally see someone posting a video of this cuz i sure as hell am not gonna help the community. I work so hard why should i share my hard work... Jk i just dont have the necessary tools to post that stuff up
lulz