I would score whatever is on the scan-tron, as that is what will happen on test day. As someone who had an error on test day, they can be devastating, as you also know. If you are double checking, where are you making your errors, what section?
Definitely bubble page by page in LR, and try subvocalizing when you do it. So read the answers back to yourself from the test book and then repeat the sequence as you record them on the scantron. See if that makes a difference for you.
I would say score the test twice, once with the error and once without. That way you see what you could have gotten without the error and also have a good reflection of your actual understanding.
The videos are working fine for me, but I know on Sunday myself and a bunch of other people could not access the site, I kept getting Gateway Error message.