Vig is short for vigorish (or another term for "juice"): what the book charges you for placing a bet (eg. -105 versus -110 at another book) there.
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"For example: This example assumes odds of -110 (11 to win 10)
Bettor A risks $110 to win $100 on Side A, and Bettor B risks $110 to win $100 on Side B. The winner receives $210 from the sportsbook, and the loser receives nothing. The sportsbook made $10 on this transaction. The total amount booked is $220. The total amount paid is $210 ($220 - $210 = $10). The vigorish cost for this hypothetical wager is 4.55%. This is because $10 is 4.55% of $220. Had the bettors bypassed the sportsbook and bet against each other then there would be no vigorish fee. The winner would receive the entire $220."
Source:
http://www.smartcapper.com/article_vigorish.html
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Also Matchbook is a betting "exchange" where you place a bet and the book charges a "commission" for that service. The commissions at Matchbook are better than a standard book vig because it is a flat rate, versus the books altering the vig to their liking. A minor problem with Matchbook is that I don't see a way of making parlay or teaser bets there (probably a good thing.)
I may be wrong here - please correct if so.
There are a number of low vig or low "juice" books out there, but be sure to research the stability and reliability of those books before depositing there because a lot of them are scam books.
At Bodog you are paying more on the vig, but the book is a stable book regardless of their other problems (dual and late lines, slow payouts and adequate customer service at best)
As for your card, Capital One appears to be a decent bank, but something is still strange that Capital One will allow on line sportsbook deposits at Bodog. If you can do it, more power to you as long as Bodog accepts the card as legit when you send them the verification info that Bodog requires.
If you can use the card at WSEX or Matchbook, and your card is legit, I don't see any problems - but you will likely have to verify the card with those books as well. Also, if the books deem the card to be a fraud, then they can (and will) take away your deposit and winnings.
GL.