Some Merlin YouTube links:
A beautiful multi-shippy Morgana vid done to that Bat for Lashes version of "I'm on Fire." Very pointed and beautifully edited. The moments the vidder picks for the cuts in the lyrics... Wow.
From the same vidder:
A Merlin-centric vid, but with Merlin/Arthur (and hints of M/A/M/G)
And
this one just made me crack up. Merlin/Arthur