There is one more command (to be sent on 8889) needed to get a playable video stream:
0xcc, 0x58, 0x00, 0x7c, 0x60, 0x25, 0x00, 0x00, 0x00, 0x6c, 0x95
It will request an I-frame generation, together with the essential SPS/PPS info - Tello will send them on the video link, port 6038.
Sending it...