I've been asked to shoot a speaker in front of a video wall and have IMAG of him on the wall behind him. I let them know that video feedback is going to be a big issue but the effect he is going for would be pretty cool if we can pull it off. Is there any filter or technique to eliminate video feedback?

Hi - I'm not a video guy, but maybe you can use greenscreen/masking to overlay the speaker in front of the video wall..? I've attached a course on video FX to this thread, in case there might be something useful in it -- maybe a video guru will weigh in with some advice..