This is achievable by using a BillboardGui (if you want it to pop out of the screen) or a SurfaceGui (if you want it to be directly on the screen). Then put the gui in the surfacegui/billboardgui.
First, insert a block. Then add surfacegui (you can do so by clicking on that plus icon next to the block in the workspace when you hover it and search “surface gui” then add it) to the block now scale it however you like-there’s distortions. Now, insert any video from inventory or toolbox. Drag and drop the video into the surface gui. Open properties of the video and scroll down until you see loop and play video. Enabling loop will make the video nonstop playing and enabling play video will allow it to actually play.
For ServerSide :
You can make a MouseClicked event on the button and then make a RemoteEvent for changing the channel.
For example you can stop all of the other videos other than the selected channel(or make them invisible).
Then you can play the selected channel.
For ClientSide(only visible to player)
You can basically do the same as above but you dont need to create a remote event and a serverscript.
Just make the other channels invisible and you’re done.
Also to add a video on a part, you can basically add a SurfaceGui into that part, and add a VideoFrame.