Thank you guys for clearing things up... I have experiment throat grip little bit, don't feel any difference, maybe need to try more.
PhrygianDominant, I think in that video, I have few, very few forhand are straight arm, most times are not 100% straight. I don't think I am modelling after anybody right now. I was trying to get Federer's forhand tho. But after all these years with double bent, i have developed my own swing pattern and I don't think I can change it... So I just apply straight arm discipline to my current swing pattern. I know it is not perfect but It seems work out pretty good so far. 1 of my old tennis partner, we have not played together for a long time, thinks my stroke are so much smother than before... And I used to record my hitting sessions all these years, when I compare, my current forhand is a clear winner... more smooth, more power and more spin...