Thanks for applying!
This has to do with an "introduced bug" in getting the channel username upon submission. It affects a very small % of submissions. YouTube used to have only one type of standard alphanumeric username, but has since change their API to have 3 related settings. It's probably related to using a Google+ username. Basically, the submission came through, but the link was munged and there is no way for Sam to know the correct channel without asking for the corrected link.
Sorry for the confusion!
