I've read a ton of fixes all over the place, including here, and none of those fixes apply. My wife and I just got an A23 each, and neither of us can send videos through Messenger. No, it's not the file size, or the data, or the WiFi. Never had this problem with a phone before. I'm seeing where you should click the 3 dots in the corner of messages, but there aren't any. That's just one issue of many I've had with this phone, but I won't complain about those because I'm sure there's no fix for those either.