YouMVOS: an actor-centric multi-shot video object segmentation dataset by Wei, D, Kharbanda, S, Arora, S, Roy, R, Jain, N, Palrecha, A, Shah, T, Mathur, S, Mathur, R, Kemkar, A, Chakravarthy, A, Lin, Z, Jang, W-D, Tang, Y, Bai, S, Tompkin, J, Torr, PHS, Pfister, H