Hi Harastean,
There's some good stuff on SubGuru.com which really helped me out:
Landlubbers Survival Guide for Dangerous Waters, v0.6
(Good all round info for rookies to be used in conjunction with the manual)
OneShot's P-3C "Orion" Dangerous Waters OWTOP Version 1.3
(Great info for the MH-60R also, really good for learning how to use sonar bouys effectively)
Plus there are lots of resources regarding TMA.
The download page is here:
http://www.subguru.com/downloads.html
Also, it really, really, really helps if you can print out the manual pages and resources you will be using for a specific platform, so you can refer to them in-game without having to alt tab. (Or look at them on a tablet/2nd comp alongside the game.)
And... There seems to be a real lack of decent videos re: dangerous waters. But, this chap who goes by the name 'Cobrabase' has made some good ones. They're quite entertaining too...
http://www.youtube.com/playlist?list=PL3DCB3ABFBFB20394
Hope this helps!
And yeah - I thought the video tutorials that came with the game were pretty useless too, however the manual is good and well written.