Looks obviously fake from frame 1.
The video looks fine.
There are no hallmarks of being a CGI or a doctored video. All of the details in the background and foreground and relative interactions to the environment are exactly as we expect it, as are the details of the aircraft as they move.
Doing all that modelling for CGI or doctoring it, would probably be more expensive than simply filming some routine flight trials/integration between the given 055 and the helicopters
Furthermore, showing a takeoff of Z-20J and Z-20F from a 055's helipad is entirely within expectations of what the PLA are willing to disclose, and is something we've been expecting.
The only "abnormal" thing about the video is that the helicopter taking off from the helipad in the first part of the video (taken from the helipad deck) is a Z-20J, while the second part of the video (taken from amidships) is a Z-20F.
We can tell the difference based on the sensor fit on their belly and nose, where the Z-20J has a nose downwards pointing EO ball, while Z-20F has a nose upwards pointing EO ball as well as a distinctive belly mounted surface search radar.
That means the two clips are depicting different events, taken at different times, but they spliced them together to look like they were one event.
However that doesn't mean the imagery is CGI or doctored, it was just a frame sequencing decision of real footage.
Having vigilance for CGI and doctored imagery is good, but this clip (apart from splicing together two different events of Z-20J and Z-20F taking off and making it seem like one) looks completely normal to me.