Feb 9, 2018
I have a good news for you. On my Macbook Pro With vlc video playback software version 3.0.0, it came out as a solution to the sync problem. I just updated vlc to 3.0.0 and happly found that the audio / video problem was fixed.
Feb 16, 2018
Just to make it clear, why the delay exists: The Bluetooth profiles of which the BOSE products are capable of, do not have the Qualcomm aptX chip on board!
Therefore you always get over ~120 ms latency (delay) when listening. While this is no matter when you have audio only - you will notice this latency very much in a combined video and audio feed (videos, movies, games ...)!
With aptX (available as "aptX", "aptX HD" and "aptX Low Latency") you would get down to ~40 ms latency. To get it straight: This is a hardware (lacking of chip) matter and cannot be solved via firmware! With firmware improvement you might get down to ~120 ms but not the ~40 ms of "aptX Low Latency"!
But as you might know, BOSE does not use Qualcomm aptX at all! Check https://www.aptx.com/products and try to find BOSE in the very long list of brands. Not present!
A further explanation to the delay with the "SoundSport Free": The right ear-piece has two bluetooth modules built in. The first connects with the player device (smartphone, TV ...), the other one streams the left channel to the left ear-piece. To get this synchronised, a special mechanism is in place, which favours synchronicity of left and right channels (which is truly most important) versus delay.
The SoundLink Revolve and Revolve+ users know this from the "party mode" or "stereo mode". You cannot watch movies with this setup, the delay is too big. Single Revolve/Revolve+ via Bluetooth is fair, but two connected Revolvers is unbearable. This is why BOSE recommends the AUX connection for best low latency experience.
Needless to say, how disappointing the lack of aptX in BOSE products is. Although very good products. Personally I favour the BOSE products over the rest, but the missing aptX stuff is truly a no-brainer (in this segment of pricing)! aptX is not just latency, but also sound quality.
Feb 7, 2018
I too, prefer the Bose over all of them and that's why I decided to keep them....the only thing about reading what you wrote about the lagging issue, for me, not sure about anyone else, is that it ONLY lags on youtube (that I noticed so far). It does not lag from movies that I have on my iPad, not from Netflix, not from watching movies from apps like FlexPlayer or PlayerXtreme. The lag is not everywhere, just isolated to YouTube, in my situation.