I know nothing about You-Tube -- and between you and me, I am not sure I *want* to know anything about it!
So hopefully someone else will answer that aspect of your latest query.
As for the DVD aspect, if you did you editing and then went straight to Share > Create Disc, that could have been the reason the burn did not get all your audio filters -- particularly if you inserted that filter late in the edits and then did not save your project. That is because that workflow inserts the project file as it was last saved in the burning module. So it will only burn what was in the last saved version of the project file.
That is yet another reason why we always recommend that people do all their editing, and first (as you did the second time round) go to Share > Create Video File > DVD and save the whole project as a new DVD-compatible mpeg-2 file.
Note also that after you produce your new mpeg-2, you go to File > New Project. Don't worry about giving your new project a name. The objective is just to clear the timeline of your current project.
Once that is done, you select Share > Create Disc > DVD. The burning module will open. Use the Add Media button at the top to insert your new mpeg-2 in the burning timeline. Then go to the middle of the three icons in the bottom left of the burning screen. There is a little box beside the words 'Do not convert compliant mpeg files'. Make sure that box is ticked (it usually is by default). That way, your already compliant mpeg file will not be re-encoded. Then build your menus and burn.