I have received more info from the casino insider.
The city of Reno has various video poker games with over 100% return. You can see some listed here: http://www.vpfree2.com/casinos/by-re...eno-tahoe.html
The locals love these machines, but in reality they are more of a gimmick than anything else. Most are low limit, and it is assumed that most players will also make mistakes and/or misclicks, bringing their expected win under 100%.
However, casinos are aware that there are computer-like video poker players who almost never make mistakes, and have a deep enough bankroll to withstand variance.
Stephen Paddock was one of those players, and in fact was regarded as one of the best, when it came to avoiding mistakes or incorrect strategy.
He loved the multiplay machines with the 100%+ return. He was beating the casinos for a long time, and had a deep enough bankroll to withstand any variance. In fact, he was observed being emotionless while playing. Even when he had bad sessions, he showed no frustration, and didn't seem to care much.
There was at least one casino in Reno where he was an overall winner over an extremely high number of hands, and probably more than just that one. (I know which casino, but I am not naming it, as I've been asked not to.)
He played video poker all over town, especially at places which ran 100%+ games at any reasonable stakes. (That is, he didn't play the 5c or single-play 25c machines.)
One casino even downgraded the 100%+ return 100-play machine they had, because he was consistently beating it. This disappointed some locals who enjoyed that machine, as the casino observed that only he was able to beat it over a large sample of hands.
He wasn't making huge money, however. The casinos aren't stupid enough to offer 100%+ games at high stakes, and it's still a big grind to make consistent money on a machine with a 100.xx% theoretical return. Clearly Paddock enjoyed the grind and spent a lot of time doing it.
He also played sub-100% games (hence his high status at Caesars), but focused most of his video poker play on the better-paying Reno properties.
Interestingly, he had a bad week recently, about a week before the shooting. He lost more during that week in Reno than they had ever observed him losing before. I was not told if his play style changed at all, but simply that he lost a lot, and that it was unusual. However, the amount he lost was unlikely to be significant enough to break him or cause serious financial damage, given what we know about him (and his ability to withstand variance in the past). It was only notable because of how bad the run was in such a short time. Was he perhaps playing poorly because his mind was on what was coming up?
FYI, Reno is quite far from Mesquite (over 500 miles), but he also had a property in Reno, which was searched by authorities after the shooting.