Apparently, Cawl is a Welsh secret because it cannot be viewed in the United States. From the ingredients, it looks similar to a dish that my Swedish relatives would make, although I don't know what it was called.
Well the video isn't available but I googled it. It looks like stew. One recipe called for beef brisket and another lamb. Vegetables that I've never added to my beef stew rutabaga, leeks but cabbage I would try. Caerphilly cheese seems to be prevalent in a couple of recipes. Never heard of caerphilly cheese I wonder what it taste like. The definition of 'cawl' doesn't fit by Merriam-Webster. A basket basically. So 'stew' would be a more appropriate meaning in English to me. This is going to be fun to say instead of stew.
I've not cooked with rutabaga, but I've used turnips and parsnips in stews...you can't make oxtail cawl without turnips.
I didn't pay a lot of attention to recipes or ingredients when I was a kid but my parents were Swedish, and they used turnips in a lot of stuff. Rutabaga was also common.
I don't know where I first started eating turnips. We never had them at home. As an adult, I grew to love raw turnips with a bacon/horseradish dip...they are like very mild radishes. (Parsnips, on the other hand, are bitter...but they have their place in stews.) I just read that rutabaga is also called "Swede" in England and "Swedish turnip" elsewhere. It's sometimes referred to as "turnip" (Scottish and Canadian English, Irish English and Manx English.) A cooking site says that it is "the signature ingredient in Cornish dishes." I might have to pick one up and make a root veggie stew before the weather warms up...I've not made oxtail stew in a while.
A bit off topic, but rutabaga is supposedly a cabbage-turnip cross and it stores much better that turnips. I have grown all the above stuff mentioned by @John Brunner. Parsnips are not bitter if they have been subjected to frost prior to harvest, as the cold stimulates the plant to generate sugar. We can sometimes overwinter parsnips in the ground even here. Root crops are good survival foods and were grown to feed people and livestock for centuries.
There are even collectable cawl spoons: I bet @Sir Walter Pasty knows what a real spurtle is (even though it likely is not used in Welsh cooking.)
I think they're not quite the same thing, though, because I think we had both. Rutabagas were mixed with potatoes as ingredients in pasties, which were Cornish in origin, but popular throughout the Upper Peninsula of Michigan.
We hold the rutabaga in high regard in my immediate family as a holiday celebration vegetable but I recently made one just cuz it was in the back hall. (sort of our cold storage.) I did not have success growing them as much as Canadians seem to. the ones I buy from there are HUGE in comparison. I have a special knife just for cutting and preparing these monsters for cooking. The parsnips we grow, on the other hand are HUGE and sweet after frost, John. Don Alaska is right. . Almost too sweet for me.
I ate plenty of root veggies as a kid on the farm; I remember rutabagas being more yellow-fleshed than turnips. Not sure if that was just the variety or what, but the taste/texture is similar IMO.
Kohlrabi. Not really a root vegetable but still very tasty. I use to plant around 100 kohlrabi plants.