Still going with this nonsense? Forget LOOSE grip. Think RELAXED or moderate grip pressure. Your video does not advance your claim. Don't know why you think it does.
Pro players tend to employ less grip pressure than low-level rec players. Studies by researchers, such as Jack Groppel, have demonstrated that advanced players employ grip pressure that is moderate / relaxed for most of the swing. This type of grip pressure facilitates superior strokes. it also minimizes forearm and hand fatigue.
Numerous studies show that grip pressure
at contact has NO bearing on ball speed. In studies, it has been shown that a clamped racket (tight grip) and a free-hanging racket (very relaxed grip) had the same effect on ball speed. Note that this refers to grip pressure AT contact (not prior to contact).
Grip pressure prior to contact can have an effect on RHS and on the quality of the stroke. It appears that the only advantage of a tight grip is a reduction of racket twisting AFTER impact. But this twisting has NO effect on the quality or control of the ball.
https://www.semanticscholar.org/pap...ppel/8b2342d268bee73f26398978be6f6a75605b4839
Two conditions simulating the extremes of grip firmness (zero vs maximal) were compared... results indicated no significant differences between post-impact ball velocity for the two conditions. Therefore, it was concluded that previously reported concepts regarding striking mass and grip rigidity are no longer tenable and that the influence of grip firmness in activities in which hand-held implements are used is important only in terms of post-impact implement control. Potential adverse physiological/anatomical effects related to over-gripping are suggested.