The Fin supports .mp4 files. 
Do a search in Google for a freeware program called  "Any Video Converter"
Go to YouTube search for the vids you like. Highlight and Copy the URL to the right of the vid.
Paste the URL in the Open Field in Any Vid Converter. Then Click on Convert.
Copy and Paste the Converted file which will be located in My documents/Any Video to your video folder on your phone by USB Data Cable.   There you have it. Vid on the Fin
Spent about 2 or 3 hours yesterday getting  Bullet for my Valentine and Slipknot.   NOTE: some will not work due to the type of file the Original vid file. However I ended up with about 30  vids on my phone.

Hope this helps.

I assumed "fin" was referring to "finesse"? am I wrong?

I have the video converter on my computer already and I use it to convert dvd movies to my ipod. I will check to see all I know is this it's not right that they have removed all access to do anything with this device espcially since they are behind on all applications. They want you to only use their metropcs store to purchase products so we have not unlimited ourselves. I will try this but what about photos? How do you take photos and pull them from the camera to your pc to share with others? except by emailing them to your email 1X1 and that is a lot of work. Same thing goes for the videos you take with this thing.

vixy.net has an online video converter as well as a beta version u can dowload to ur computer. its as simple as 1:copy &paste vid url
2:wait bout 60 secs for converter to finish.
3: transfer vid to micro sd via my_videos folder.
always works for me!

why does the samsung instinct from sprint plays youtube videos perfect and the finness does not?