Vizio now has available a 21x9 format television, in an attempt to catch up to the ever-widening format of the movie theater (which ironically keeps widening in an attempt to differentiate itself from television).
TV started out roughly the same aspect ratio as the movies at the beginning. TV was roughly 4x3 (a ratio of 1.33) and the movies were 1.37, just a touch wider. Most television shows from the beginning of black and white until sometime during the 5th season of the X-Files are all the 1.33 ratio. Some TV shows in the last 10 years or so are in a 16x9 format (a ratio of approximately 1.78 ). Movies over the years have utilized quite a number of different aspect ratios, as different film companies and equipment manufacturers sought to differentiate themselves. The ones most commonly encountered at the movies would be 1.85, 2.35, and 2.39. (If you don't watch any movies before 1970 you can skip 2.35.) As far as your DVDs and Blu-Ray discs go, just check the back cover where it has the info about the languages and the rating and the surround sound and you'll usually find the ratio listed.
So, let's perform some basic calculations to quantify exactly how crazy it is to watch video of various formats on various screens. Let's start with an old-fashioned 4x3 TV program on a 21x9 screen. This one's pretty easy - a 4x3 ratio is the same as 12x9, so the 4x3 program would cover 12/21 of the screen - about 57%. Next a 16x9 picture on a 21x9 screen - again, pretty easy - it's 16/21 or 76% of the screen area. Cinemascope (the current after 1970 variety), with a ratio of 2.39 is a touch too wide for 21x9, so with only a tiny bit of letterboxing , it fills almost 98% of the screen. If we do the same sorts of calculations for a 4x3 TV, we get 100% (of course) for 4x3 programming, 75% for 16x9, and around 56% for Cinemascope, somewhat the opposite of the 21x9 scenario. Running the numbers a third time for a regular 16x9 widescreen TV, you get 75% screen coverage with 4x3 footage, 100% (another of course) for 16x9 programming, and 74% screen coverage for Cinemascope.
It would seem that if you watch a variety of formats, that a 16x9 TV is the sweet spot where you can still get a lot of screen coverage, and that a 21x9 TV would only be advantageous if superwide movies were all you had. I'm sure the hardcore cinephiles that really want this 21x9 screen don't have to worry about watching too many standard old-school format TV shows, but I think the rest of us are not much worse off sticking with regular 4x3 TV's if they still have them (except in one area, which I'll have to save for next time). When it's time to get a new TV, I hope that a 16x9 is still the sweet spot and we haven't all been coerced into heading into ultrawidescreen land.