{modal url="https://www.youtube.com/embed/OiYjoaHIWyc" width="560" height="315" title="Modals - Getting Started"}This is a Youtube video{/modal}
{modal url="https://player.vimeo.com/video/347119375" width="500" height="281" title="Sample Video"}This is a Vimeo video{/modal}

Please note that you can only use this feature if your website is running in SSL (https) mode.

Quick links PRO

Just like with the articles, the Pro version of Modals provides you with the ability to create links to videos with a shorter syntax. You can simply place the youtube / vimeo video id after a youtube / vimeo attribute:

{modal youtube="OiYjoaHIWyc" width="560" height="315" title="Modals - Getting Started"}This is a Youtube video{/modal}
{modal vimeo="347119375" width="500" height="281" title="Sample Video"}This is a Vimeo video{/modal}

When using the short syntax with youtube or vimeo attribute, you also have the ability to set the video in the modal to automatically start playing (Autoplay). You can do this by adding a autoplay="true" attribute:

{modal youtube="OiYjoaHIWyc" autoplay="true" width="560" height="315" title="Modals - Getting Started"}This is a Youtube video{/modal}
{modal vimeo="347119375" autoplay="true" width="500" height="281" title="Sample Video"}This is a Vimeo video{/modal} 

Please note that autoplay will not work on certain browsers and in certain conditions.
See here for an explanation on the Autoplay Restrictions:
https://vimeo.zendesk.com/hc/en-us/articles/115004485728-Autoplay-and-loop-embedded-videos