Hello everyone.

I have a small web developing company. Me (as the designer) and my friend (programming engineer).
Recently, we had build a website (includes educational content) that has videos in it.
On the page which the videos are shown in groups, when I click on a video it plays normally. But when I click on the others the previous one won't stop and continues playing with the others.

How can we fix this problem?
Any help will be appreciated.