There are five things to note:
1. The player flying JF-17 used poor tactics to begin with. @GrowlingSideWinder is a great player who knows what he is doing. So, yes I am bit disappointed with the results, but do understand that it has a good deal to do with the man behind the gun.
2. JF-17's Achilles heel has always been the power-plant. That is why its TWR is lower than Mirage 2K. If it had a significantly more powerful engine, it would take the fight into the vertical plane and dictate the fight despite having comparatively less maneuverability. Depending upon the improvement in power-plant output for JF-17 Block III, the disparity would be eliminated or reduced.
3. JF-17 is not an air-superiority fighter. It is based on a number of compromises that were dictated to Pakistan during the development of JF-17. It is what we could put together. The alternatives were either to not have anything or to break the bank trying to procure something cost-prohibitive.
4. The gun fight is a very special case. First its going to be BVR and if that does not precipitate a result, then the next stage would be Short-range missiles (with HOBS, HMD/S); and only after that would we see a gun fight. So, the replication of circumstances with one-on-one merge like that is not a probable scenario.
5. We do not know how accurate is DCS exactly. It can not possibly model all sort of scenarios that would realistically take place with true capabilities of JF-17. Most likely, JF-17 would be part of mixed packages that would include F-16s.
So, a youtube video is not the end of the world for JF-17. I would not be too worried.