Isaw is a chicken intestines, betamax is grilled blood cubes, gizzard is basically grilled chicken gizzard, Pork intestine, Liver etc.
This is also called as Ihaw-Ihaw. In the Philippines this food is a very common food, every afternoon you will see this in the streets.
It is a very popular snack in the Philippines.
If you will be able to visit the Philippines you will be able to see this stall.
And you might enjoy this food :)