If it was not long ago, you could have a look in your history of visited websites. However, if you have cleaned stuff or deleted history it's probably lost. Also it depends how long you have it set to save history.
Maybe if you said what the video was someone could point you in the right direction.
To find a page you've seen in the last few days
On the toolbar, click the History button.
The History bar appears, containing links for Web sites and pages visited in previous days and weeks.
In the History bar, click a week or day, click a Web site folder to display individual pages, and then click the page icon to display the Web page.
F A B Scott