I get that site maintenance message as well. I think the trick is when you hit okay on the message and it takes you to the gofile main screen to go to the guest bit on the left and press login. Then go back to the original video file and it should work because it's now logged you as a different guest account.
I had to do it earlier and I think those were the steps. Hope you get what I'm saying, if not I'll try and explain it better if I have to do it again. I'd need to see it in front of me to work it out again.