The Costco one is nice. Those DK2 are at Home Depot.
I think I might be a little too early as most of these aren't in stock yet.
By early, I mean I might have to wait another couple of weeks for the spring sales/inventory to come in.

If you are going to be carrying any dirt/rock/shoveling material.... you'll still want to get some cheap sheet wood to put down to keep from scraping/scratching the shit out of it and starting the rust process.

Does that trailer have provisions for raising the wall height?

I can't tell and was wondering that myself.
Watching the video it looks like what you see is what you get.
Left side, click on the one like this:

https://www.homedepot.com/p/Detail-K2-1295-lbs-Capacity-4-ft-x-6-ft-Flatbed-Trailer-MMT4X6/301207694?MERCH=REC-_-PIPHorizontal1_rr-_-204187355-_-301207694-_-N

Doesn't look like any easy way to raise the sides.... really limits it usefulness. You'd have to rig something up to make it sturdy. Funny to see them load a (fullsize) quad in it.... most fullsize quads are just over 6'.... and no tie downs... thats a pretty bad idea...
They don't say anything about tie down points --- using the rolled edge for straps is going to last only so long before the sides get folded in....

A trailer that can only handle 1200 pounds is a toy. I built one that I would haul behind my Triumph with an 800 pound limit but the most I put in it behind my bike was #300. You will soon out grow a 1200 pound limit trailer. I have four trailers. The smallest has two snowmobiles on it. The next is a tilt bed former boat trailer with an extruded steel bed that will handle a ton. I use this trailer to haul my small tractors or lumber. I also have a box trailer made out of Studebaker pickup bed which works well for hauling small loads of fire wood or gravel. Next I have a triple axle trailer that I built 17 year years ago just under 8 ft wide and 12 feet long it will handle four tons. Originally I had a 3/4 inch pressure treated plywood deck. The plywood lasted for five years before it rotted so I went to extruded steel. Lastly is my car trailer for hauling cars and trucks and my dozer and when I need to haul 20 foot long pipe. Do not get in a hurry to buy a trailer. Keep your eyes open and you can find one that will do a better job then the ones you have posted photos of. What do you have for a tow vehicle? Go on Craigs List in your area and look at what is available.

The search is over.
I scored something extremely worthwhile.

Detail K2
1639 lbs. Payload Capacity
4.5 ft. x 7.5 ft.
Galvanized Steel Utility Trailer with Bed Tilt and Collapsing Ends

Oh... I didn't pay that much.

Good choice! CL score?

Actually Offer Up.

Even came with a tongue jack.

Something I learned yesterday at the DOL.
They give you a choice of which license plate you can have. "Huh?", says I.
You can have the full size plate like the cars have or you can have the small plate like the ones on m/c's.
Cool, gimme the small one. I don't want anyone able to read my plate.

The small ones are great for a trailer.... the big ones always get bent to hell - especially with a dumper.