The biggest thing I can see, from watching your video, is that during F2L you're turning the sides WAY too quickly. I cannot over emphasize how much so too quickly you're turning the sides. Your solving is very choppy during F2L and this is caused, again, by turning the sides so incredibly quickly. When you turn that fast it doesn't allow you to look ahead to the next pair at all.
The analogy I am going to use is speed chess. In speed chess, the players have always thought a couple, if not several, moves ahead of what the board is showing. Speedcubing is
exactly the same way. Your mind should always be a couple, if not several, turns ahead of your hands.
As an example, try one exercise. I want you to go to
www.metronomeonline.com and set the metronome for 40 beats per minute. Every time the metronome beats you have to do a turn. If you miss a beat, then you have to quite literally stop your solve, rescramble, and start all over again. Try to finish the F2L doing this. Do this 20 times in a row. After doing that, do a regular speed solve and see what your time is. I guarantee that it will be a fast solve for your average. I really am not joking. Try this out and see, you'll be surprised. I'm not trying to come across as harsh, but you asked the question of how to improve your solving time and I am giving you the answer that will help you most.
One last thing, the turning speed you use for OLL and PLL is fine. Keep that up! Only
slow down during your F2L! I want you to let the following phrase become your mantra during F2L: "Slow is fast". I'm really not joking that making just this one small change will improve your average by 10 seconds or more, easy.
Hope this helps,
Chris