Bump up video size max for previews to 100MB

Hello! Big fan of Discord here, recently the Nitro file size upload limit was increased to 100MB, double the former 50MB. However, the previews for videos are still capped at 50MB. Video previews don't show for videos over 50MB even though they can be uploaded.

This would be great change to let Discord users enjoy the 100MB file upload limit more, since they'll be able to viewer higher quality videos within Discord.

Please consider this change! Thank you!