Complex sentence: At age 7 he started his dance training at the Ensemble V. Lokteva in folk dances, and while there, he appeared along Oleg Popov in the film "The Sun in the Bag" (солнце в авоське).
Split into simpler sentences: At age 7 he started his dance training at the Ensemble V. Lokteva in folk dances. While there, he appeared with Oleg Popov in the film "The Sun in the Bag" (солнце в авоське).