Can you please have a look if there was a change made to Alexa Developer Console 1-2 days back that broke video playback using APL directives?
Currently Console can't play video on M, L, XL Hubs. Video works normally only on S Hub.
Two days back video was playing fine on all types of devices, however now only two seconds of video gets played and then video gets frozen but audio continues. Please note that S Hub under Developer Console is not affected and everything plays fine there. Also everything plays fine for all types of displays under APL templating utility (Skill -> Build -> Display).