I very much enjoy my 2nd hand bought Kala U bass. If you make multiple screen vids like me I would recommend added U Bass because the regular high pitched uke can use some bottom.
The instructional bass videos of Stephen are very clear and informative and
Stephen is the only one on the entire planet teaching U bass in videos and online.
I used one of his instructional vids on his Jazz blues video, Spaghetti Blues
That is also tought here for uke in RC101.
I found it easy to play simple pop songs that just require the root, just one one single note every bar. So the step up is easy.
Stephen has easy but also more sophisticated songs on the web, up to you.
So if you want to enrich your uke skills and make your vids more fancy go for Stephen!