I am putting together a Halloween video and for my final shot I want the camera to pan over a bunch of portraits of past presidents of my university. When it gets to the current president, the camera will stop and I want the photo to come to life with him saying, "Boo!" or something similar. Does anyone know how I would achieve this effect? I've seen some tutorials where you will simply transform a video into the frame of the picture, but it didn't look as realistic as the others. Any suggestions? Should I shoot the video in portrait instead of landscape so it fits into the frame better?

Maybe. You may also want to run the frames through photoshop and make it look like more of a painting.

You can try going old-school, and project the image/movie onto/into the picture frame area from behind, then you film the film

And say just no to vertical video

Vertical Video Syndrome - A PSA - YouTube