He was talking the eneloops, but I doubt he charges them 2000 times in a year. For me, I'd use the eNeloop pros because they are good for 500 recharges and carry a greater mAh rating resulting in significantly longer play times in between recharging.
Now, this brings back to me the issue of having quality chargers. A good charger will easily double the life of batteries. When I was doing the photography thing and always had a TON of batteries that needed changing, I purchased two chargers that could handle 8 AAA, AA and A batteries and each socket in any combination and could do slow, fast and re-conditioning charges. The reconditioning part took a long time (left it go overnight normally) and that added a good 6 months to the batteries to bring them back up to full capacity. I still have those chargers today and they continue to serve my needs.
It's no biggie if you have 10-20 batteries to charge, but on a typical wedding photoshoot (15+ hour day), I had to have (typically) 100-120 batteries at full charge and ready for me. On an average wedding day, I would come home and nearly all batteries were very well used. Just in flashes, I had 10 battery operated flashes with AA powered receivers (60 batteries per single use right there)... lol
All that is major overkill for an FR-4x, but in the above case, we are talking about a musician that gigs not only regularly, but several days a week, so his methods assure that the 4X always has reliable power and the issue of battery reliability is never a concern... to this I say well done!