motion effect help

Hi,

Motion newbie here...
I was wondering how to create the effect where the video clip plays within a certain particle effect and not in the background. for example, making a choosen video show inside the "heat ray" particle emiiter effect so that it looks like the video is being projected with that effect. does this make sense? sorry if i don't

Sure, use an image mask. Select the video clip in the Layers tab, and choose Object>Add Image Mask. Then drag the particle emitter (assuming you already placed it in your project) from the Layers tab onto the image mask, or into the well in the dashboard or the Inspector. Set it to Alpha and you should be good to go.

Mark