I have set the max file size in php.ini to 1 GB and I still can't upload a 107mb mp4 video

This will be the member group level settings for uploaded files. Go to AdminCP > Members > Member Groups > Click the pencil icon to edit > Content tab > Uploads.

I would recommend keeping the max_file_size and post_max_size around 8MB (which is pretty much the default). Having these settings too high will decrease performance and may cause problems when uploading large files.