For Desktop Version :
Step 1 : First login to your facebook account.
Step 2 : Once you are logged in to your facebook account you can see a small blue downward arrow click on that and you will see many options there
Step 3 : Now click on Setting and you’ll be redirected to the General Account Settings page
Step 4 : Now you can see a option called videos on the left hand side of the window Click on it.
Step 5 : After clicking on video you will be taken to the new page where you can change your settings for videos. Here you will also see an option Auto Play Videos which is ON by default. Select Off to disable the feature and from now videos won’t be played automatically.