Ipod Nano and Classic supports H.264 video, MP4 video and .mov video with a maxmium screen resolution of 640 X 480 pixels. Your ipod will not play videos on other format and you will not be able to add them to your iTunes Library also. I have attached a video which I have converted from YouTube to iPod and I used it on my iPod Nano.
Download iPod Video>>>
You can use third party software to convert your other videos format to iPod format.
You can now get your Apple products like, Ipod Nano warranty information online. If you have purchase your product from Ebay, Yahoo, Classifieds or other websites, you may check the Apple products by keying in the Serial Number and the Country. If you do not have a sales reciept as proof of purchase, it will follow the default manufacture date as the start of your warranty period.