All the Iphone/Ipod Touches have the builtin YouTube App, but is that sufficient to see other videos? That app doesn't even have much of the videos available in the desktop version. So here's a neat trick to see videos available in other sites(needs a quicktime player). So the first one is, watch video in Google Videos . In your Iphone/Ipod Touch, open a browser and type in a search query in the google search box. After you get your results, go to your address bar, it will say something like, [www.google.com/search?q=(your video)&ie=UTF-8&oe=UTF-8&client=safari]. Now scroll to the end of your address bar and then delete [safari] part. Then you will get a regular Google Search results. Then click on Videos . You will see your results, but you dont want to click on that says youtube.com because that will take your to native youtube app. So search for the one that says videos.google. you will get a flash player not found picture and then on your right side, you can see "Download Videos Ipod/PSP" Just wait for a couple of seconds, according to your bandwidth speed and then you will have a QuickTime player playing your Video.
Thats just the first part...
The second really helpful site to see videos in Dailymotion . But the thing you need to look after is, when you go to the page, it pops out a dialogue box saying asking if you want to transfer to its mobile site. Just press No/Cancel and proceed. If you accidently pressed YES and want to go to desktop version, clear out your History, Cookies and Cache from your Settings>Safari on Iphone/IpodTouch
Pros: All the videos play in Quicktime player.
Cons: kinda slow and sometimes crashes safari and have to click "cancel" on every page.