Haha apparently I'm an old cuber now. I started in April 2012, first comp in January 2013, so maybe "borderline old" is a better term.

Keep in mind that I was ~12 years old at the time, so I'm sure I did things differently than the older/more experienced cubers of the time.
What lube did you use?
I first used Silicone spray on my Rubik's brand, and I had to go in my garage to do it because of the fumes. I took the whole cube apart, set the pieces out on a newspaper on the floor, and sprayed Silicone spray all over it. I let it sit for a while, then put it back together, and man did that thing turn well afterwards.

Later on I got some Lubix, and I still love how my Lubixed cubes feel.
What did you use as timers?
I used CubeTimer as my first online timer, then I eventually switched to qqTimer, and later csTimer. My first Stackmat timer was a Gen2.
What was the best speedcube/where did you get your cubes?
The best speedcube was definitely the DaYan ZhanChi. I only had a Rubik's brand and a DaYan GuHong V1 when I went to my first 2 comps, but I had to compete with the Rubik's brand since the GuHong was stickerless and not therefore legal at the time. At my second comp, a kind experienced cuber told me I should get a ZhanChi to compete with, and it was an amazing cube for sure. Later on the FangShi ShuangRen came out, and that was the first possible ZhanChi killer. I still love that cube, and honestly I think I could get my usual times on it today if I had a magnetized version. I honestly don't remember where I got my cubes, but I was young so my parents got a bunch of them for me as gifts. I definitely bought from most cube stores at one point or another.
Did cubing channels exist at that time?
Cubing channels absolutely existed, but the biggest ones (like RedKB, CrazyBadCuber, and MeMyselfAndPi) only had ~30K subscribers. YouTube as a whole was significantly smaller then too though.
Where did cubers socialize/where did you talk?
I personally chatted on Google Hangouts with my cubing friends, since I wasn't on other platforms like Facebook yet. Speedsolving and Facebook groups have existed for a long time though.
How much did cubes cost?
Good question, I think 3x3 speedcubes would generally be 15USD or so, but it varied a bit.
How did you make cubing videos?
I recorded my first cubing videos with my Nintendo 3DS (lol) but again, I was young at the time and I didn't have anything better. Eventually I moved on to a low-quality camcorder, then I finally got my hands on a smartphone to record with.
How popular was cubing?
I thought cubing was really popular at the time, but it's nothing like it is today! I'm from New Jersey, and I was allowed to sign-up at the door at my first comp - in recent years I've organized two comps in NJ and both of them have filled up in a couple days.