In my care i flight about 15 batteries times (2 hours) and four baterey leds are on yet... sorry that is not an answer... but "a lot". Ah in about two months.
I usually record my complete flights until baterry drains out... so I have several tens of more than 8 minutes videos. The short ones were properly recorded? If you use the gamesir remote... perhaps you press the "pause" buttom during the recording?
If the wifi link is "bad"... you need low bitrate to avoid frame drops, if the link has good quality you can use hisger bitrates. The auto mode will select the best options for you depending on wifi signal strenght, so Auto.
...Javi
The bitrate is related with the transfer capacity between yout tello and your phone. If you set it to very high value the image quality will be better but if the connection is not able to trnafer all data you will skip frames. If you set to low values... images will be worse but it will be more...
Welcome. You are right. The tello is an amazing piece of hardware. I think that the firmware and app could be improved a lot!
Enjoy your flights and your visits to the forum.(y):)