We were uploading videos and disabling comments in YouTube v2 via the access control elements:
&l
Disabling comments and ratings on a video is not supported by the v3 API at this time. There is a known issue where if you disable comments on your videos in your channel preferences and then upload a video through the v3 API, comments are still allowed on the video (note that this bug was reported internally, but it does not appear to have been fixed). YouTube is still working out these features for v3.