I picked up a free Sony 4 head VCR, a tape was stuck in it. After I pulled out the stuck tape and cleaned up the VCR it plays fine now.

I was looking at the bad tape (Ernest Goes To Jail) and theres what looks like mold on the tape itself?

Is this common? I've never seen a moldy tape before.

I have a stack of umatic and Betacam tapes in quarantine that are all moldy. Yes it is a common thing.
Make sure you clean the transport, drum and tape path with alcohol before putting any other tapes into that VCR as you can spread it to other tapes.

It was cleaned with alcohol, greased and given a new home. The cassette door keeps popping off... I guess it will remain off.

Sticky shedding tape syndrome. Google it. Think it applies more to reel to reel tapes than video, but you being in a humid area I would say yes that it is indeed mold

Sticky shedding tape syndrome. Google it. Think it applies more to reel to reel tapes than video, but you being in a humid area I would say yes that it is indeed mold

I agree. RTR (reel-to-reel) audio or video tapes (this may also apply to tapes housed in cassettes) may become moldy in very humid environments, but shouldn't if humidity is normal. I live in northeast Ohio, where the humidity is generally medium due to my being within one mile of the south shore of Lake Erie (the highest I've seen here is no more than 60 percent, and that is normally in the summer; right now, as I write this, the relative humidity in my apartment is 57 percent).

Mold on any kind of magnetic tape (audio or video) can cause excessive wear on tape heads, so I would be very careful if there is mold on your tapes. I have no experience with this, as all of my audio and video tapes (the few I have left, as just about all of my music and video are now on CDs and DVDs) are in cassettes (I gave up reel-to-reel long ago) and have never had trouble with mold on any of them.

BTW, as was mentioned, tapes stored in high humidity areas are more prone to developing mold than those stored in normal or low-humidity areas. However, if you do notice mold on your tapes, be sure to clean them thoroughly before using them. As I said, mold on magnetic tape can cause wear on tape heads, so it is very important to keep the tapes clean if at all possible.