Serious Glitches with a basic video

I won't be purchasing the premier rush mainly because I seem to have had way too many technical issues with the app. On my phone it was constantly pixelated and I only did like 3 transitions and it was a 30 second video with music added. On my computer it was slightly different. It kept glitching and shaking then crashing on the screen , going different colours then I even saved it. That then came out as a black out video with no noise at all. I tried to do this 30 second video numerous times removing the app then re uploading and nothing helped.

I heard others had  similar problems and that just scared me in to even purchasing. And paying the monthly fee. 

such a shame because it looked good.