Comment 4 for bug 1784242

I can also confirm the issue.

Software: fresh Ubuntu 18.04 installation
Computer: Dell Latitude E6510
CPU: Intel(R) Core(TM) i5 CPU M 540 @ 2.53GHz (Ironlake)
Test file: H264 1920x1080

totem: shows only green screen, no video playback

mpv: video does not play smoothly + following is printed to console:
Audio/Video desynchronisation detected! Possible reasons include too slow
hardware, temporary CPU spikes, broken drivers, and broken files. Audio
position will not match to the video (see A-V status field).

mpv --hwdec=no: plays perfectly - ca 60% of cpu is idle

vlc (video output set to "Automatic"): video does not play smoothly + following is printed to console:
[00007fccb4c1a930] avcodec decoder error: more than 5 seconds of late video -> dropping frame (computer too slow ?)

vlc (video output set to "XVideo output (XCB): plays perfectly - ca 55% of cpu is idle