exercise in madness LOL :)  Loved the process and your determination.. I have had to invent a similar rig for Film cleaning - many good books back in the day how to build your own rigs ect.  Had a good little business for several years in the early 90s cleaning all those super 8 films people wanted to transfer en masse

A low speed drill with wood or cardboard gears to adjust the speed ratio for a controlable pace. A holding frame setup with a long bathing trough for soaking and lots of time, patience and hope.

What you need is a "Wet-gate" video playback system ;)

I have never seen any type of tape with that amount of mould on it, I have used a scrap VHS recorder to clean tapes successfully, your idea of using a scrap miniDV camcorder is probably the best option.
It would be interesting to try it, but as you point out, it would be a lot of work & probably the tape would still not be recoverable.

On the Rank Cintel mk 3 telecine there was a cleaning device that had two rolls of tissue paper running around a couple of rollers that the film was dragged between as it was shown. The tissue paper is fed automatically from a small roll constantly but slowly to clean the film. If you could get hold of one and rig up a way to feed the tape though in a motorised way it would probably work. Might need a few passes. It's not like the film cleaner in the video.

Remove tape completely from spool, submerge in an ultrasonic cleaner with proper cleaning solution added, let the power of cavitation remove mold, respool and enjoy.

Like making a delicious miniDV tape noodle dish.

Maybe window cleaner spray may do the job with a very soft cloth

Leaving the uncoupled tape to soak in an isopropyl alcohol solution bath overnight then attempting the cleaning process

Maybe some aggressive household cleaner would have delivered some better results, but then the residue of the cleaner would have needed to be cleaned off as well. Another question comes to mind, there has always been that debate about wet and dry lubricants on MiniDV tape. I could imagine the mould and/or cleaning the mould makes the lubricant not work anymore, or takes it off the tape. Maybe that was why the tape after cleaning stalled the head drum? It was however quite interesting to see how the mould on that one tape made the path of the video heads across the tape visible.

Hi Colin - I believe I have your name correct...(?!) You sent me a box of VC/LVC tapes some years ago..
My reply here, if it's of any use with the moldy tapes is that years ago, I too had moldy MiniDV and 8mm camcorder tapes that were just a mass of picture static when I first tried to play them..
At the time, I had something I had built that did work successfully for awkward tapes of all sizes.. A dehumidification  unit. Basically, a large plastic box with two 9V dehumidifiers sat in the base, wires through the box and sealed air-tight with silicone rubber sealant. The box had a rack fitted within it on which I sat my tapes. An air-tight, hermetically sealed lid meant no additional air could get in or out of the unit. At only 18volts, I would leave this for upto five days. The air within would be processed and reprocessed through the tapes, super-heating the air molecules in the box.  After five days, it had sucked the air and tapes warm and dry. The previously no picture/no sound MiniDV tapes now had both picture and crystal clear sound.
I did eventually disassemble the unit when I bought an Andrew James Food Dehydrator - and have since used just that for all my tape baking..

What about warm water, sometimes we forget the simple stuff can work.

I heard concentrated hydrogen peroxide cleans mold better than rubbing alcohol but they are only available through chemical suppliers. If someone knows how to 3D model, pretty sure they can design something simple with motors and can run the tape continuously across a cleaning pad.

Wonder if there's some element of lubrication on the tapes which is being attacked by the mould, and the cleaning process, that you could somehow replenish?

hi good video   why do people let there tapes get like this  so easy to put them away right

I would suggest running through a UV light . The question would be on duration and intensity of the light. A cheap UV LED Nail Lamp maybe ?

a small bath at the beginning of the tape path with some iso in?

Have tried dishwasher detergent mixed with hot water in higher concentration?

I have an idea. Since miniDV and CVC use 6mm tape, why not spool the miniDV tapes into a CVC shell and clean them using a CVC machine in FF/REW mode and a piece of rag soaked in IPA? That shouldn't hurt the machine since it fast forwards and rewinds with the tape unlaced.

I would actually try an open reel in play speed. Or its about time someone fabricates a table top cleaner with variable speed capability. I have the idea of design perhaps I can share it with you.

Can use UV light for clean