Why is Embed Restricted to Certain Domains

edited 11/12/21 in Smartsheet Basics

Why can I not embed whatever I want into a Smartsheet dashboard? I want to embed a timer, but it won't work because it is not on the list of approved domains... I don't understand why it is restricted at all.

I was attempting to embed the following code:

<iframe width="250" height="125" src="https://vclock.com/embed/timer/#countdown=00:02:00&date=2021-11-12T11:06:47&onzero=2&showmessage=0&theme=1&ampm=1&sound=twinkle" frameborder="0" allowfullscreen></iframe>