You have to record a show on the DVR or Tivo or similar in order to watch without commercials.
So does a high school diploma cover all subjects then? And are they graded?
Most schools do quarters, and you get a report card for each class for each quarter. My son right now is taking Spanish, Geometry, Biology, English, Computer something, Art, and History. When he gets his report card in October, he'll get a grade for each of those classes for that quarter, and he'll get a new report card for each subsequent quarter, then in May he'll have a final report card for each class, which is the average of each class for all four quarters.
As long as you pass each class, you get credit for it. You get your diploma and graduate as long as you've achieved the minimum number of credits. So, the credits are cumulative for four years of high school. I graduated early, because I took advanced classes, which are "weighted," meaning they are worth more credits than an average class. You also have to meet the minimum course requirements to graduate, you can't just take four years worth of art and music classes and graduate, you have to take a minimum number of math, English, etc.
That said, different school districts do things differently, so what my local schools do may be different that what others do.