I have seen more than a few auctions over the years with COA's from them and people are always in deep discussion about authenticity of their items.
I say, if you do not know the company or cannot find any reliable positive feedback about them online, then stay away.
COAs are worthless, unless they are from a company/individual you can actually contact.
Their own COA says it's only valid for 30 days, and they were issued back 2009 it looks like (at least one of them), so again, it's worthless. If the person on the COA isn't willing to stand behind the item FOREVER, the COA is worthless... (And that probably means he doesn't really know himself, one of those 'a friend said it was authentic' type things.)
There is a name, address and phone number for the person that issue the COA, did you try calling them?
The Ebay ID has been NARU'd over a year ago, although I don't see any negative feedback in the first few pages... Looks like he specialized in celebrity 8x10s and random smaller props (Ocean's 11 poker chips, stuff like that)
But the question you should be asking is if the _props_ are real, not the COAs... I can print a COA that looks just like that, and I can pair it up with a piece of junk I made myself, or a real screen-used prop... Doesn't mean a thing. And if you buy the spiders, reframe them without the COA, that just looks stupid (IMO of course ).
Additional Googling shows the owner of Hollywood Rock-n Country (Scott Velvet) is the owner of a Pawn shop in Missouri and is also the owner of the Celebrity Car Museum in Branson, MO: http://celebritycarmuseum.com/
His current eBay ID is the_velvet_collection, so you can see the kind of stuff he currently sells.
You might be able to contact him to see if he's willing to provide information on where he got the items you are asking about. item history goes a long way to proving something is authentic.