I do it the traditional way of video downloaders. Click the video > Share > Copy video url > Go to video downloader > Paste > Download video. My video downloader is Vidmate, an older version.
Why not just uploading from the app?
I use v 0.90.5-play, didn't find this possibility.
New post, first button (image with a plus). Make sure to navigate to a video on your phone.. Or use built in android "share to..."
Doesn't this button work? https://image.nostr.build/f1596a044d232b23ee75ffd296e26a7bd07fea9f0afc6af4acd781264aea0c87.jpg
ah, this option not so obvious for me :) https://image.nostr.build/7a08e5fe760ab5f29dd85eba22f71a6434f4125a4f019902c002c71bef7e063e.jpg
It takes way longer. Nostr.build is instant.