First you need to upload them to a video sharing site like YouTube and then get the HTML code for embedding into other websites.
For example, on YouTube you need to get the HTML code by clicking the "Share" button, then select "Embed" and copy the generated HTML code that should look like this:
<iframe width="560" height="315" src="//www.youtube.com/embed/9bZkp7q19f0" frameborder="0" allowfullscreen></iframe>
1) Then in NiftyQuoter click the source button

2) Insert the HTML code provided by YouTube or another video site

3) Click the preview proposal button

4) The video appears

Please note that videos cannot be played in PDFs!