My laptop wont play videos online anymore

About 3 days ago my laptop stopped playing videos online. some videos cause the browser to freeze, whilst some just dont work.
When i try and play a video off youtube it takes about 5 minutes, then starts playing. but when i try one off itv player or something it simply wont work.

i have had my computor checked for virus' and deleted everything like that. i have delete my browsing histroy/temporary internet files etc. and now i have run out of things to try!

i have a samsung r530 laptop, if that helps. and it isnt that old (only got it 5 months ago)

please can someone help me.
i am not that good with technological terms, so please can you explain it in simple terms

thank you so much for reading, and please can you help.