When you embed media, such as a video, Google form or search widget into your guide, LibGuides uses a "container" called an iFrame to display the media on your page. One way to make iFrames more accessible is to add a title, so the user knows what they have encountered on the page.
In the site view of a LibGuide, an iFrame will look similar to this:
In the rich text editor, though, it will look like one of the following:

This method applies when you have embedded a video into an existing content block, aka in the same box as your page content.
For each iFrame on your page (which should only ever be embedded videos), right-click on the object and select "iFrame Properties".

Decide upon an informative title for the video and add this text to the "Advisory Title" field.

This method applies when you have embedded a video by adding it as a content block to an existing box. If it is done this way, you will have added it from the following drop-down:

If you were not the one to add it and don't know if your video was embedded this way, you can confirm this in the following way: if your box text and this video are edited separately, this method applies to you.
Click on the editing drop-down in the bottom-right of the box:

You will be greeted with a screen that looks like the following:

In the "Embed Code" section, add the following text in next to the other attributes like "width" and "height" (separated from them by a space): title="descriptive text about this video"
Then click "Save".
