Improve Alerts & Error UX

[prastut]

Alerts:

• [ ] Give user info that we only support file uploads less than 30MB.
• [ ] Give user info that we only support hevc format only (https://github.com/livepeer/file-video/issues/19#issuecomment-756665517)

Error's:

• [ ] Provide errors if the user still bypasses the above alerts.
• [ ] Do them client side only, before sending the file to the Demux's gateway.

[prastut]

Hi @adamsoffer, is this something you could help us with in improving client-side UX?

Users are facing a lot of problems because the above UX isn't there, see their concerns below:

1. https://github.com/livepeer/file-video/issues/19#issue-780247418
2. https://discord.com/channels/423160867534929930/426106677650128898/796295804087828531

Demux faces this problem as well inside Livepeer black box:

1. https://github.com/buidl-labs/Demux/issues/30#issue-738179700

[adamsoffer]

Yes absolutely. Thanks for bringing this up.