I've uploaded two of the files, but aborted the script then because I apparently didn't call it with --comment-ext. I'll continue the uploads tomorrow (but not now, as one of the files is locked as I aborted the script, thus I can't start another attempt to upload it immediately).
Finished the upload now.
The file format was fine this time, yes. I can't say anything regarding the max. file size that one can actually upload, but I know that several people struggle with files well below 1GiB.