Embed/Link Video
To embed view Adobe tutorial here http://kb.adobe.com/selfservice/viewContent.do?externalId=tn_15777&sliceId=2 but if you wanted to link, I guess you could upload videos to video hosts like Youtube etc and just link/embed their player-- won't cost you any webspace or bandwidth.

Forums
Their are pleny of forums you could use that are open source and free for you to use. Some hosts may actually have them available for you to install with one click. Check out phpBB, Invision Board or vBulletin.

Webhost
Any good host would share ALL those attributes. I can recommend totalchoicehosting.com just for that. I have recommended them many times as a quick search will show on these forums here. They are good for...

* 99.9% uptime
* 24/7 live support (good and helpful support)
* latest cpanel
* frequent back-ups for websites
* very inexpensive

~Sovereign