The FLIR doesn't have that much more features. dB and dBm with no way to change the reference voltage. Low Z, a low pass VFD filter and a couple of LEDs on the side. The 71 has a 4~20mA % and a Pass/Fail feature. It still doesn't account for such a huge price difference.
I'm not sure you watched the video properly or you would know that in 4,000 count mode, the 71 is as fast as the FLIR (They use the same IC).
Please, the 61E is a POS. It drifts all over the place. Get a proper voltage reference and you'll see. It's just a 2,000 count meter at best. My 71s, using more expensive components, have been rock steady over more than a year now.