Still sceptical
I apologize if I had underestimated the radar capabilities of the DFFD airport tower before. If the video from FranceInfo is not fake, it appears there is SSR coverage, but still I doubt it would be utilized operationally. The squawk 2000 hints to this assumption, too. However there is no mentioning of the radar installation in the AiP.
The loss of contact was reported to have happened after 48 mins flying time. This would mean that the aircraft was about 300 NM from the radar head or even further. This is below the radar horizon of any radar, so I am still sceptical what I see.
The video is very much accelerated. The SSR turning speed may be 10 or 12 secs, assuming this is not a brand new state of the art SSR only installation ( it would not need the big dome then). The video shows two or more updates per second.
The video consists of three sequences:
(video time - flight level - ground speed are the data below)
1) climb out sequences
11:19 FL116 310kts
level and GS gradually increase until
11:24 FL147 350 kts
I would say that this corresponds to a normal flight profile.
At an assumed climb rate of 2000 ft/min within 6 seconds of video the aircraft climbed 3100ft, so an assumed acceleration of 10x or 15x could well fit.
2) level flight sequence
11:25 FL310 410 or 400kts
until
11:28
This corresponds with my knowledge of an initial FL of a heavily laden MD80
If this is not fake then the ghost target could be a result of the aircraft flying well beyond the radar's nominal range
3) final sequence
11:28 FL305 330kts
This constitutes a significant drop in ground speed, maybe to the vicinity of Vs. But remember that ground speed on radars is derived by calculation of the leg distance between the past radar positions, so it may be inaccurate
11:29 FL298 310kts
11:29 FL295 300kts
11:30 FL295 280kts
11:30 FL295 270kts
11:31 FL252 270kts, aircraft starts veering left
11:31 FL252 150kts, tight left turn
11:32 FL252 140kts
11:34 the target disappears, may have fallen below the radar horizon or transponder not responding