Unfortunately, it appears he appears to have conflated the percentage and absolute returns on the base game and bonus spin when doing his calculations. This is clear as obviously $155.30/300=$0.5178, not $0.0414 [which is $155.30/(300*$12.50)].
Summing things correctly, you get an expected return per round of $0.52+$3.51+$3.20=$7.23.
Alternatively, at $12.50 per card you generate percentage returns per round of 0.041+0.281+0.256=0.578.
These numbers are quite high as over two rounds they would generate a positive return on any card purchased for less than $14.46, but a good chunk of that value derives from a free cruise with a likely value of well under $2000 and casino free play/match play that is less valuable than cash when used (and much less valuable than cash when not)!
