There is a new way of embedding video clips on this forum. The existing methods still work, but the new way allows us to embed clips which previously didn't work when using the existing methods.
On the source website, look to see if there is an embedding option. If there is copy the embedding code. then on this site, click on the HTML icon at the far right of the row of icons and paste the code on the resulting screen on a separate line after the code already shown. Then click on the Update button at the bottom to get back to the normal posting box. You should see a box shaded yellow with a little box in the middle, You can carry on typing more if you want.
Make sure you don't infringe any copyright.
Although this method could already be used, it's been changed to make it possible from more source sites than before.