Hey Hive account@thatdude
Please don't use your normal Steem password credentials on DTube.
DTube is asking that you use your STEEM user name and your STEEM "Private" POSTING key... which you'll find under your Steem Wallet>Permissions tab.
The key that immediately shows as your Posting key is actually the Posting public key, not the private one.
You'll notice off to the right of that key, the blue box stating "Show Private Key".
If you click on it, it should take you to a pop up to unlock your account once again, using your "main" login details, and then it will reveal what your current "private" Posting Key is.
Now would be a good time to change your Posting Key password to something different from your main.
BE SURE YOUR "POSTING PRIVATE KEY "IS NOT THE SAME AS YOUR MAIN STEEM ACCOUNT KEY!!!
If it is... CHANGE IT to something different from your main login.
Once you've verified that your POSTING key is completely different from your OWNER key... then your good to go to use your Posting private key on DTube.

AGAIN... VERIFY THAT YOUR POSTING KEY IS COMPLETELY DIFFERENT FROM YOUR OWNER KEY. Otherwise you've just publicly published your main Steem owner private keys.

Hope this makes sense and helps?