Change viewport resolution will crash unreal when play video in runtime mode

when i play the video player in runtime mode, and change the viewport size (like press F11 to fullsize the viewport), unreal will crash.

Same here! if the resolution of the game viewport is changed when some media source is being played, unreal crashes.

Yeah, sorry, there is no simple fix for 4.15 and 4.16. The problem has been addressed in Media Framework 3.0, which will hopefully make it into 4.17.