Oh man -- I swear, I have this exact same episode of ET on video tape stashed somewhere in a box for the same reason you have it - coasters at Magic Mountain. This was definitely the mid-80s at its best.
Funny that the American Eagle at Great America (my home park) was still the tallest when this aired. The Eagle opened in '81 and its hard to believe it held the title of tallest coaster for so many years - especially given the recent decade of coaster wars where holding any kind of title (height, speed, etc.) for more than one year was a feat.
Thanks for digging this one up and posting. It really brought back some memories.