Use mp4 as the source stream

Enable HW video decoder and use it to decode video_device.mp4. Currenlty
the end of stream (EOS) has error that causes problems for looping, so
disable looping for now.

Bug: 151393184
Tested: edgetpu_demo --device
Change-Id: I6695014476613d46fd78f3d3cc17edfdc13c75d9