Hello,
I went through your project description and understand what you want.
You are basically looking for a Google App that will authenticate the user, take permission to get their channels and upload videos to the selected channel. Videos will be uploaded directly from your website to the user's channel.
You can also use the code through a cron job, but in that case the app will need a special permission for offline access. You will have to get a refresh token, save it somewhere and use that to make offline api calls.
I'll also be providing thorough documentation so that everything is clear.
I would like to know one thing : What is the average size of your videos ?
Regards,
Vayne