Hello 'mycatlea12',
<< Is this legal ... Why did ebay allow this to go on sale?>>
It depends. If the film is in what is known as "Public Domain", such as a lot of those early movies and tv shows, then yes, it is perfectly legal to copy and distribute it. As such, you can go to any major retail outlet and buy a legal dvd in which the print quality is so poor as to be unwatchable. That is because it may have been copied and recopied many times. You will see this a lot in those 'multi-movie packs' of old films where some are of a reasonably good quality and some are dreadful.
Here is ebay's policy on Public Domain material:
http://pages.ebay.ca/help/policies/public-domain.html#policy
And that is why ebay allows it to go on, -- because there is nothing dodgy about it. You will often get a poor quality version and if it is a particular film you are seeking you may have to do quite a bit of scouting around for a first rate one. A good quality copy will cost more than a poor one.
That said, as you did not indicate the title you purchased, if the item is not in public domain and is being copied for resale, that can be reported. Again, see the above link.
Another thing you need to know about dvds is that if you buy from a seller outside Canada & the US you may be buying a disc that will not play on standard North American players. Do you have an all-region player?
Some discs are listed as "all region" but they, too, will not play on standard N.Am players. Usually, however, you can play them on your computer, but I realize that is not always much of an option.
If you are unhappy with the disc, and if it does not play for you, you can sweetly and politely contact the seller and explain your disappointment. Perhaps you can come to some arrangement or maybe you would like to mail it back for a refund.
When you return an item you need to use tracking or else a seller can say it never arrived and you cannot prove it did. Tracking is extremely expensive, even just for an envelope, especially if the item is to go overseas.
See for yourself what Canada Post rates are:
https://www.canadapost.ca/cpotools/apps/far/business/findARate?execution=e1s1
And a third thing, -- always always always read the entire listing from top to bottom. Sellers constantly gripe that buyers don't read the listing. Thus, it behooves sellers to limit the amount of babble and be clear and concise about item description. But if the seller mentioned a taped-from-tv disc in his listing, well, you can hardly complain about quality if that information had been readily available. Moreover, how do you know if the disc "turns out to be taped from TV" if, as you maintain, it is "unplayable"?
So if you have not already seen ebay's brief info page about what to do when there's a problem,
http://pages.ebay.ca/help/buy/item-not-received.html
For now, though, I'd say just contact the seller and gently explain that you are unable to play the disc. Be nice, -- if his description is honest it is not his fault if it won't work in your machine. And if you didn't spend much money, either re-sell it or toss it in the bin to go to Goodwill along with all those titles you don't like enough to watch a second time.
Best of luck 
