WordPress has a list of pre-approved sites that can be used to automatically embed content into a Text Block using the URL of the associated site. This document will discuss some of those options.
WordPress Core functionality includes the ability for users to automatically embed items from certain sites (for example, YouTube) by simply copying and pasting in the URL into a Text Block page element. Below see some examples of sites that you can use this for:
You can grab the YouTube URL directly from your browser's address bar and past that into your Text Block.
Videos from Kaltura (https://mediaspace.wisc.edu) can also be embedded. In your video, click on the Share icon below it and select the oEmbed option. Copy that URL and paste it into the Text Block of your page to display your video.
A Twitter feed can be embedded into a Text Block the same way, however you lose the ability to customize the feed when you simply paste the URL into your text area.
Remember you cannot customize this feed using this method, so the default list will show the 20 most recent tweets. You could also refer to this Knowledge Base document to customize the feed more: [Link for document 83301 is unavailable at this time.] .
You can embed a single Instagram image into your site using this same method. Please note that this will only work for an individual image, not for an actual Instagram feed.
You can embed a single Facebook post into your site using this same method. Please note that this will only work for an individual post, not for an actual Facebook feed. You can get the individual post URL by clicking on the timestamp of a particular post.
There are many other "whitelisted" sites that can be used to embed items directly into a Text Block. There is no guarantee that this will remain the same as WordPress Core functionality consistently updates, but this is a site that lists all that are potentially usable: https://codex.wordpress.org/Embeds