Click the video page with the mouse, and then press the ← and → keys with the keyboard.
Some players have different shortcut keys by default, such as Storm Video and Thunder. Look at Ctrl+→ Ctrl+←, pptv is fast forward and fast backward, Tencent video.
There are also some web videos that don't support fast forward and fast backward.
Pptv shortcut key
Tencent video shortcut key