select 
a.video_id,
round(sum(if(timestampdiff(second,start_time,end_time)>=duration,1,0))/count(*),3) avg_comp_play_rate
from tb_user_video_log a
left join tb_video_info b 
on a.video_id=b.video_id
where year(start_time)=2021
group by a.video_id
order by avg_comp_play_rate desc