Keno often offers very high casino advantages (I think often they are in the range of being over 20% and possibly it could be closer to 30%) and so it's not a great game to play. Video Keno can offer lower casino advantages to be faced (at least in Las Vegas it can offer a casino advantage of about as low as around 5%), but it is played at a much faster rate than traditional Keno. With Video Keno, it can be played as fast as your being able to play 2 or 3 or more games per minute (if you don't change the numbers) whereas with regular Keno, it's played at a slower rate between games (at least several minutes between each game).
There is a Keno Calculator (which will tell you what the return on a game is as well as its Variance [which is basically its Volatility Rate]) available for people to use on the
http://www.wizardofodds.com website. From there, you would go to the "Games Calculator" link and then from there go to the Keno link. With this, you would have to input what the different hits are paying to receive an answer about the game's return rate as well as what its Volatility Rate is. See below for such calculations on different 4 Spot pay schedules that are in Las Vegas.
What you are paid for the different hits for Traditional Keno will differ from casino to casino. But with Video Keno, pay schedules can and very well do differ from one machine to another machine even within the same casino.
For example, with Video Keno, you could find pay schedules for a 4 Spot (I have seen all of these pay schedules on machines -- and they actually are all in the same one casino [Plaza Casino in Downtown Las Vegas] although in different locations of this casino) where there are machines that pay 2-5-68 (Return rate = ~84.98%, Variance = ~15.37), 2-5-77 (Return rate = ~87.74%, Variance = ~19.32), 2-5-91 (Return rate = ~92.028%, Variance = ~26.45) or 2-5-100 for 2, 3 and 4 hits respectively. In this example, the 2-5-100 pay schedule would offer the highest return rate (its return is ~94.785%, Variance = ~31.67).
And so with what I've written above, you can see that there is a range of Video Keno game returns offered with these pay schedules that has the return running between about 85% and 95%. This can very greatly affect your return.