I haven't tried the applying video to a bitmap approach, but there is another way you can solve the same problem. You could use a video component and an image component. The image component will sit on top of the video one. You can give the video component an instance name, and control it with getElementById. Like this:
var video = document.getElementById("videoname");
Canvas background = transparent
<div id="dom_overlay_container" style="z-index:-1">
or just add in body
<video src="myvideo.mp4" style="z-index:-1"></video>
I don't think I can use image components because I have alot of keyframes and stuff in my movieclips/timelines, wouldn't that mean I have to convert all of that? And then I wont be able to get a proper preview it would just look like a ton of grey boxes ?
Look at marjantrajkovski's suggestions, those seem hopeful.
How can I use that for a specific video with a precise size / location?
Could you perhaps supply a full example ?
The part I was saying, about using a video component, would solve the position and size issues (you can resize and position the component to fit in the right place for your animation). Doing the index -1 and transparent background canvas would solve the other part of the problem.
By the way, you can tween a video component on the stage. It would be possible to have a video playing and also tracking a moving gap in your animation.
Yes, as Colin mentioned, you can place a video component and set its desired position and size on the Animate stage itself.
Now make the stage background color as transparent and add the below line of code in frame scripts:
dom_overlay_container.style.zIndex = -1;