When watching a video, check for the gear icon. If it’s available, click on the gear, and you’ll be presented with a settings menu. Look for the Playback Settings menu as highlighted here:
Click on the Playback speed selection in the popup menu, which as shown here indicates that Normal playback speed is currently selected.
You’ll see a selection of various playback speeds to choose from. Normal speed is effectively 1.0. 1.25 would be 25% faster playback speed. 0.75 would choose a playback speed that slows playback by 25%. Adjust the speed to the desired playback rate. Choose the “Custom” link for additional values in between the choices shown in the Playback Speed menu.