I don't want to spoil anyone's day, but a FLIR could also be a passive or active EOIR sensor in the short wavelength band, i.e. not the everyday thermal radiation domain. Granted, short-wavelength Russian IR systems were apparently able to pick fires at great ranges (even lighted cigarettes for infantry systems), but certainly not the thermal radiation of a running engine.
Or it could also be a first-generation FLIR (in the US sense) that was tested on the Mi24B but abandoned for lack of reliability/efficiency/affordability. Hell, the thing didn't even reach the prototype stage, nothing even tells us that this LLTV/FLIR existed when the Mil team put the mockup together!
All in all, it is strange indeed that the device isn't mentioned in further versions.
I know, I'm Hind-prejudiced...
