When I import .mp4s renders from blender they crash my other applications. I think there is something wrong with the encoder.
exporting s avi jpeg then converting videos is another application seems to work better.
Hmm. I’ve made several mp4 renders in Blender 2.8 that work without any issues in other applications, so it seems that the encoder does work, for me at least.
I’m not sure what is causing your problems, but you haven’t provided any information to help people help you.
Which operating system are you running Blender on? Which applications are crashing? What are your encoder settings? Can you upload a problematic .blend file? Without this type of information it is very difficult for anyone to help you.