Are you able to upload a pdf of the score? I can kind of guess what most of the instruments are but its really hard to read at the size in the video. I'm guessing the instruments above the strings that have the sixteenth not figures at the beginning are various mallet instruments? I like alot of the ideas you have here, I think they are just in an unrefined form. For example, I think the opening passage would be very hard to balance, with about seven different instruments on the sixteenth notes and the melody in just one flute. Since all the mallets are marked ppp, maybe reduce it to just one and leave the winds out of the sixteenth notes? Just an idea. I like some of the melodies that use more exotic scales starting around 1:34 as well. I don't think you should necessarily shy away from larger ensembles, but maybe limit the scope a little bit? Since it sounds like you're pretty new at this, maybe just try a some shorter, well-defined forms (binary, ternary) with fewer layers until you get more comfortable, then expand as you get more experience. Focus on just having a melody, bassline, and some chords, then gradually expand into more complicated textures. Also, think about the instruments you are using and how they will fit into these roles. Instruments like basses, cellos, bassoons, tuba will generally be baseline; violins, upper strings, trumpets will generally be melody; horns, and trombones will generally be chords; etc... Keep these roles in mind as you write... and of course different instruments may have more than one role from time to time. Thanks for sharing.