The book of 18 Études, by early 20th century French clarinetist Paul Jeanjean, has always been in my repertoire. I began studying these while in high school, continuing through the first two years of college, discontinuing my study of them when I transfered to Northwestern, where the emphasis was on orchestral repertoire, not solo performing. Though the move ended up being a productive one for me, as it helped me get the orchestral job which carried me through my career, I never gave up on learning all 18 Jeanjean études someday.
A few years ago I started a project to perform them all, over a period of time. (I doubt anyone wants to hear solo clarinet études for an hour and a half) One of the first ones I tackled was #2, which has eluded me for years with its sea of notes in the second part. The awkward technical passages, built on augmented triads, forced me to revisit hand position, finger accuracy, quality of air (to create flowing legato) and steadiness, both physical and mental. The hardest part of this étude is staying free while playing the blur of notes in the second part (second video)
For the record, I recorded this with a Canon Power Shot camera, not intended for long video recordings. I had to record this étude in two parts because the whole 4 minute work wouldn't record seamlessly on my Canon. I intend to get a better recorder soon.