Nothing funny about it actually.
IN.VC is definitely a premium domain and easily worth more than the EU 220 that it was listed for, in your Sedo account. There's nothing wrong about the Sedo commission though, as .VC is a category III domain for which their
stated minimum commission is EU 150.
You did not renew the domain on 15-Dec-2010, at the same time you did not remove it from your Sedo domain list. So, when the sale came through on 06-Jan-2011, you would still be listed as the registrant. The name wouldn't yet have been released to the registry. So, you became party to the sale process. It is a common thing that many people renew their domains much after the expiry date within the permissible date range. Sedo had no way to know that you had no intention to renew the domain, unless you told them when they sent you the sale order.
Since you kept quiet (or ignored them), the transfer request was generated (by all means an automated process at Sedo) on 16-Jan-2011, their system looked up the registrar and found it to be Name.com who would have become registrar just two days before (30 days after expiry) in place of your registrar Dotster.
So, it is wrong to say that Sedo is a robber. But, yes, their system has a lacuna and perhaps such a case is a rare happening. The lacuna is that the generation of transfer request looked up the registrar but did not recheck the registrant neither did it flag a registrar change so there could be a manual review. This can happen inadvertently and surely they would correct their system, now that such a situation came up.
I had a .COM (category I, parked and fixed price) sale back in January 2010 of $499 for which they deducted 10% and paid $449. IMO, Sedo is the most trusted (and trust worthy) domain marketplace.
You are right about the other marketplaces though - majority of them seem to be interested in selling their own domains.
BTW, it is quite possible that it was the new registrant (APS) who simultaneously put in a buy order at Sedo (to cover the remote possibility that you might renew it within 30 days) while also watching or putting a domain-grab order at Name.com. What do you (if watching this thread) say APS