You place the video in the same folder(s) you use to sync photos to the iPad through iTunes; then sync. Only a few video formats are compatible, so this is very hit or miss. Quicktime .mov and MP4 are your best bets, but since each can be configured many ways, the extension is no guarantee.
There are other threads on converting videos, and since I don't remember much about it, or have the links handy, I'll have to leave you to the mercy of searching the forum. I recommend the custom Google search on the website as the most effective, in my experience.
In case you are not familiar with how to sync photos to the iPad; here's Apple's support page.
iPhone, iPad and iPod touch: Syncing photos via iTunes
If the video is on your camera you can purchase and try the Camera Connection Kit. Apple has recently expanded the number of cameras and formats supported, but I would research whether yours is known to work before spending the $30.