When you upload sth on Dtube you put the tags below the vid. These tags show up in Steemit with a 'Dtube-' put in front of every tag. So you manually go into Steemit and edit and then revise the tags to their original form removing the 'Dtube' so that your content doesn't show up in 'Dtube-xyz' but instead the respective categories like 'cars' 'bankgok' etc.
I've been having problems with some videos as well. I have one with a very high bitrate and it doesn't seem to like those at all. Still haven't posted the question though...