it is entirely possible that NVIDIA is trying to mislead the media too. Perhaps he should have pointed at the fourth monitor and said "this is your FreeSync monitor without AMD driver optimizations."
What is being demonstrated is LFC running on a monitor that does not support it.
LG 34UM69G-B has 40-75Hz frequency range.
Nvidia has said they want 2.4 range to even consider a monitor being G-Sync Compatible. This is an example of a monitor that does not fit that requirement.
He probably should have pointed at that monitor and said "This is a crappy VRR monitor".
Just FYI - The LG 34UM69G-B is flat the one in the video has a curv to it.
Oh. You are right. It was mentioned in the Youtube comments and I did not check very well. The point remains though, it is more than likely a monitor with a too small VRR range.
There is a very good technical reason for the requirement of a wide enough frequency range. It needs to be at least 2 to be able to double the frames when FPS falls below frequency range. Exactly 2 is too small because frequency needs to be more dynamic and this causes pretty much exactly what is demonstrated in the video. So manufacturers use a higher requirement, AMD uses 2.5 for LFC in Freesync and Nvidia now says 2.4 for G-Sync Compatible. Unofficial solution to these problems for Freesync monitors has generally been to manually increase the monitors range definition and hope that monitor works fine with it. This is effectively monitor overclocking and not guaranteed.
This frame doubling is the crux of both AMD's LFC (Low FrameRate Compensation) and has been part of basic Nvidia's G-Sync spec from the start. Monitor can (or is tested, specced and guaranteed to) work with a certain frequency range. Minimal refresh rate is usually 30-40 Hz while maximal varies a lot - 75, 100, 120, 144, 165, 240 Hz are most common ones.
Variable Refresh Rate (VRR) uses this entire range as opposed to a fixed refresh rate but it still cannot go beyond the range. When FPS drops below the minimum supported refresh rate simple VRR method of fixing refresh rate to current FPS (yes, technically GPU will trigger a refresh but for high-level explanation this is close enough) will no longer work as monitor will not be able to refresh at too low a rate. The solution was to start doubling frames. For every frame coming from GPU monitor gets refreshed twice. For example, when game runs at 20 FPS, monitor refreshes at 40 Hz and each frame from GPU is shown twice on monitor. This doubling may be repeated again if necessary, for example 10 FPS on monitor with 40 Hz minimum refresh rate will get each frame shown 4 times.
This is a simple and elegant solution that is not really a problem with a real wide frequency range gaming monitor - for example, the initial GSync requirement was 30-144Hz with properly low minimum refresh rate and a wide range (maximum is 4.8 times minimum). This does become a problem on monitors with high minimum refresh rate and/or narrow frequency range. There have been a lot of Freesync monitors with ranges like 48-75 Hz which AMD never bothered to tackle in any way.
In practice, such monitor with 48-75 Hz range will work well and do VRR in 48-75 FPS range but not ouside of it. Given that these are less expensive monitors and are likely to be paired with less expensive GPUs, drops below this range will be noticeable and not benefit from VRR.
