The easiest way is probably to use the Vizzie modules that come with max. In particular the XFADR could be what you're looking for. It takes two video inputs and crossfades between them, but if you just sent it 0 and 1 messages to the rightmost input, which you can trigger with bangs, you can jump from one input to the other instantly.

Or Jitter Tutorial 8.

check out the second example in the jit.gl.slab help tutorial . Lots of fun options with the different shader modes.

Many Thanks :)

I've got a question: when I'm using this cross object. is it still possible to bang each movie and change the frame randomly with the message: frame $1 ?

not sure how you have the video playback engine, but theoretically this is possible !