Well this is currently a big debate in the SEO industry as everyone probably knows, Google seem to hate webmasters who pay for backlinks on other websites. I can't really judge, I have paid for links before.
it's very risky move to buy backlinks at present time. but a backlinks still work good to youtube videos. I bought several websites with 100 000 + indexed pages and got nice results. If somebody need website with thousands relevant indexed page - drop a line