First, install the GData package in $UserBaseDirectory/Applications. Load the GData package which contains the code used to interact with YouTube (and other Google services).
<<GData`
Next, log in to YouTube. This will prompt for a user name and/or password if either is not specified.
yt = YouTubeLogin["User"->"robragfield"]
YouTube[<...>]
We can make sure it's working by asking for a list of videos uploaded to this account.
("Title"/.#)&/@YouTubeUploads[yt]
{OmetepeProfile.mov, Homer Fireworks, Tripod, Cobb Park Crit, Mt. Diablo descent, Seymour TT starts, Screaming hard drive, Descent (iMovie image stabilization comparison), Descent, Descent, Carpenter Park Cross #2 (Line Art), Indy Marathon chase}
We can also check out other accounts.
YouTubeUploads[yt, "wolframmathematica"]//Length
950
Finally, we can upload a new video to YouTube.
YouTubeUpload[yt, "/Users/schofield/Movies/carpenter_park_2.mp4", "Title"->"Carpenter", "Description"->"Carpenter Park cyclocross race"]
«JavaObject[com.google.gdata.data.youtube.VideoEntry]»
You can also specify the category and keywords.
Options[YouTubeUpload]
{Title->Automatic, Description->Undescripted, Category->Tech, Keywords->{uploaded by Mathematica}}
