Video in nostr is a f*ckn mess right now. We have several server implementations that are not working properly or have size restrictions. Uploading errors are not handled or not explained to a user. We have  specific video notes (that flare.pub/zap.stream use) which are not supported by the social apps. 

Your best bet right now is to get the creator plan from nostr.build and upload there. 
I’m currently working on an app to upload and manage your media on nostr and hope I can improve things a bit but it’s not something one app can solve alone.