Increase video upload size limit

Increase the current 400 MB video upload limit to support larger videos, especially for users publishing high-quality content across multiple social accounts.

The 400 MB limit is currently in place to ensure app stability and performance, as videos may be published to multiple social accounts, significantly increasing the total data handled. For example, 30 different 400 MB videos published to 30 different accounts could result in up to 12 GB of data being processed.