To add a video player, you can sign up for a Youtube account
Once you have found a clip you like, click Embed and then copy the code
To insert it on one of your pages, go to NEW POST, make sure the EDIT HTML tab is selected and
paste the code into the box.
Click PUBLISH PAGE
View blog to watch your selected clip
To add your own videos to your blog, you will need to upload then first to youtube and then embed the code as you have done above