Is there any value in publishing screen-cast lectures?
I would advise against doing this, even without knowledge of tghe hiring processes in SLACs (never heard about those before) or the universities you're interested in.

On principle, it does not make sense to have projects in life whose main or only purpose is make your CV look better. If you're passionate enough about this to do it for its own sake - say, because you feel available material is not engaging enough and you had good feedback from your students - then maybe it could be a reasonable use of your time. Otherwise, your days are better doing proper research, or other publicly-visible math-related projects which are of interest to you.

Also, if you got good feedback on your teaching, I doubt your focus on research will be held against you, especially since you do have a solid 3 years. Perhaps some letter of recommendation from professors/lecturers who were in charge of the courses in which you taught could serve as guarantee of your capabilities.