Another software option would be Mixvibes Cross, come version 3.0 the video plugin is included in the price. But that is beside the point.
Obviously anything is possible technically. The setup you suggest would mean running headphone out from laptop to Yamaha. all mixing to be done in the laptop. Usually I am not too happy with sound quality that way. A headphone out is not the same as a line output. but -as said- technically it can be done.
We did karaoke for many years but got tired of lugging 3 42″ plasma screens around. We had laserdisc players at first and later regular DVD players. Always with separate videomixer and audio mixer. We needed an extra person to operate it as the MC/DJ would be out on stage MC-ing and helping singers whoost lyrics, or worse, timing.
It was fun but cumbersome and I am no sure the extra pay willbe worth the extra gear and hassle. Something else you might want to consider is if you want to spend your nights listening to howling wolves (trust me, it’s not The Voice!) and drunks fighting for the mic later in the evening.
Greetinx.
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