Did it imply that the mystery 成飛jet is a manned fighter / fighter-bomber?
No. It doesn't imply anything like that, and doesn't tell us anything new.
Let's review -- for the October 2021 satellite image, things we have observed, and can surmise include:
- A tailless delta model of some sort was present at CAC, and it is roughly the length of a J-10, but with wider wingspan. Based on its geometry, it might be single engined. Based on satellite pictures we do not know if it has a cockpit or not.
- Prior to October 2021, we know that CAC has investigated and even flight tested multiple planforms for their 6th generation fighter project, and it is reasonable even at that time to guess that likely at least some of those planforms are tailless deltas.
- We do NOT know if the 2021 tailless delta model is actually a flyable airframe of some sort. After all, it's possible it could be a structural test bed of some sort, or a production method testbed. That is to say, that specific model might not be intended to fly at all.
- OTOH, it is also possible that the tailless delta model CAN fly, in which case it could be one of the following:
A) a subscale flight test demonstrator of some sort (possibly related to a 6th generation fighter project, or perhaps related to future UAV developments, or both)
B) a prototype of a new aircraft intended to be developed for production (given its size, chances are it is unlikely it is for a manned fighter, thus consideration for a UAV/UCAV of some sort can be considered)
C) something else
... However, we can also say with decent confidence that based on its size, chances are it is unlikely to be a manned combat aircraft intended for development and production. It is simply too small for it, and if it was a prototype of a new manned combat aircraft, then we would've heard it through the grapevine by now.
Of course, if we take all of the above information together, assume that the model is intended to fly (or alternatively, has already flown), then in context of current known PLA 6th gen efforts, it is reasonable to guess that it probably is related to future combat aircraft planforms in some way.
Given its size, I also would personally suspect that it is not a manned airframe, though I acknowledge that if the aircraft were merely a demonstrator then it's plausible a cockpit for a pilot is not unreasonable. But unmanned seems a bit more likely to me at this stage.
With the new AVIC promo video, all we see is a still frame on a screen, of an aircraft that might look very similar to the tailless model from 2021. It is shown in a context in the video where do not know anything else -- we don't know if it's part of a simulator, or just a representative CGI for labwork, and there are no additional details on the aircraft itself either.
In other words, it adds nothing new at this stage.