Flat serve. To single frame on Youtube use the "
." & "
," keys. View full screen and use the time scales to compare.
There are text boxes on one or a few frames. View full screen and use the time scales to compare. Two monitors?
This video pauses for 4 seconds for the frames with messages. Find the same times in the Lisciki serve clip.
Flat Serve Fault. Lisciki has a pin point stance and you have a platform stance.
These videos have a countdown time scale in milliseconds. "0" is impact in both videos. Both were recorded at 240 fps. (Kinovea can adjust for different video recording rates.) I was not able to get the side-by-side on the same video for unknown reasons. You impact the ball 0.96 second after toss release. Lisciki about 1.06 after toss release. This time varies mostly because of the height of the toss.
Youtube down sizes my camera's 336 line resolution to 230 lines, Ugh!
You are very close. It is hard to pick out issues in the upper body from that behind camera view. A close up of you upper body showing the timing of your ISR by elbow shadows would be a good next step. The body tilt left shows and the excessive knee bend shows. A side camera view will show your body tilt forward, it looks much less guessing from the behind view. ?
I believe that your head position/angle may indicate that you do not tilt your shoulder girdle as much as Lisciki or most other high level servers. ?? Go look in the mirror and with your spine vertical tilt your shoulder girdle so that the hitting shoulder goes low then high. In other words, do some servers restrict their shoulder girdles and other servers move the shoulder more? Look at the Lisciki serve and find other high speed videos that show the tilt at impact. Is your shoulder girdle more perpendicular to your spine than for high level server's shoulder girdles? The shoulder blade rises also, too complicated for describing here. These tilts also lengthen the distance between the origins and insertion of the lat muscle and shoulder position can add stretch to the lat.