The music video and song itself is very in time with each other, she dances to the beat and sings along with the words. This makes it feel as though she is performing to the person watching the video - especially because she makes a lot of eye contact with the camera. This would keep the audience watching because they feel more involved with her performance and would therefore want to see it through to the end - to see what finale she'll give them.
Her costume changes happen in time to the music, where she goes up a key she 'ups' her outfit - getting more glamorous as she goes. She starts with a black leotard and military hat, this makes her look as though she is just rehearsing and that this isn't the big performance. Then as she goes up in keys her outfits become more sharp - such as the white suit, then up to the cane and then the big finale where she rips off her trousers to reveal her body. This can make her seem sexualised, especially as the camera focuses mainly on her the further into the video it goes - but it isn't over the top and doesn't make you think twice about her motives for the video; it's simply to have a good time through dancing and singing.
Although Beyonce's outfits are low cut in this video, revealing some of her cleavage, she doesn't attract a lot of attention to it - it's not emphasised. Her legs are given a lot of camera time rather than her chest or bum, but again it isn't taken over the top. The outfits and the editing are in time with each other and the music, to keep everything flowing and efficient and not to make it look out of place or massively noticeable.