I have several videos on Youtube using the dazzle and the quality seems fine. In all fairness I have not yet applied any of my crack editing skills to the videos but they still have high quality on YouTube (after you select the "High Quality" option on YouTube)
I have one video with some minor edits:
YouTube - [TRC] Test compression quality
And to view my profile, anything after that video is all with the Dazzle(un-edited, just compressed):
YouTube - ScottishSwan's Channel
It all comes down to how you are capturing the movies, then how you compress them (I do hope you are compressing them after capture?)
If you need Help, just let me know how you are capturing etc.