Why sql is loading data infinite?

I suspect the problem is the count(distinct). I also see no use in bringing in sid or datetime.

Does this do what you want

 select count(*) as num_rows,
        (select count(*) from sessions) as sessions,
        sum( targetbuttonname = 'kredyt' ) as num_kredyt, 
        sum( targetbuttonname = 'konto' ) as num_konto,
        sum( targetbuttonname = 'czat' ) as num_czat,
        sum( targetbuttonname = 'video-voice_btns' ) as num_voice,
        sum( targetbuttonname = 'video-close_btn' )  as num_close,
        sum( targetbuttonname = 'video-muted_btn' ) as num_muted,
        sum( targetbuttonname = 'video-play_btn' )  as num_play,
        sum( targetbuttonname = 'video-pause_btn' )  as num_pause,
        sum( targetbuttonname = 'video-replay_btn' ) as num_replay, 
        sum(watchtime) as num_watchtime, 
        sum(devicetype ='Computer') as num_computer 
 from events e ;