If you want to add your own video to your MySpace profile instead of someone else's you can do that too. While in the video section of MySpace click on the tab that says "Upload".
On this page you will need to add the title of your video along with other things such as a description of the video, tags so people searching for your video can find it, and a category for your video to be placed in on MySpace. You can choose to have your video not appear in the search results if you want.
You will then have to agree to the terms and conditions of MySpace before you can upload the video. They don't allow porn and you can only upload videos you have the right to upload. If you upload something that is not allowed you take the chance of having your MySpace profile deleted.
Click "Continue" to move to the upload page.