After verbs meaning 'see' and 'hear' you can use either of these unstressed words to introduce a following clause, with this difference in meaning:
Ї слІшал, что онђ игрђет на гитђре. I heard she plays the guitar.
Ї слІшал, как онђ игрђет на гитђре. I heard her play the guitar.
Ї вќдел, как онђ игрђет в тљннис. I saw her play tennis.