Seeing that much foam on a primary to secondary transfer is a first for me! I did however once get a foam overflow while degassing after secondary by hitting the wine to heavy/fast with a wine whip. This was with wine a little over the shoulder of a 6.5 gallon carboy.
Wow. I hope my Gewurztraminer that I just started doesn't have quite that much. I stirred mine for the first two days, then airlock and into the refrigerator at about 55. My heart is only good down to 59,so I'll probably take it out in the morning and let it warm up a bit.
Can you imagine trying to get all that out by stirring? Good thing you have one of those vacuum pump things.
I've not seen that much when I used my AIO to rack to secondary unless I really rocked the carboy, but lately I've been using my siphon for this stage. I want to ensure there's enough CO2 to protect my wine in secondary. Though with the amount of CO2 I've had that's probably an unnecessary thought. Of course after secondary, all means are fair game to degas.
Once in a while I get that much action when I vacuum rack. I also have noticed if I add K-meta first to the carboy and rack hard into it I get a Lot more foam, than I do when I rack first then add K-meta. Some wines just foam more than others. Roy