I discovered a great tool for copying your productions from your youtube channel to your d.tube account. It's called : YT2IPFS. Let me know how it works out for you.
Check it out here: https://github.com/wehmoen/yt2ipfs
For downloading youtube video's you can use a script called youtube-dl: https://rg3.github.io/youtube-dl/
And you can start combining those two in an automated process if you want.