Many wireless networks are established with router settings that will not allow wireless devices within the same network to share data. Something to do with "ad-hoc" or alternative network options. Then there are also issues with firewalls and other ssharing permissions.
If your TV does not have a wireless adaptor, then it can't receive wireless
Can your PS3 see your laptop on the network? If it can then it may well be able to stream media. If not then see the comment on network configurations above and you'll probably have to read the small print in your routers manual for the appropriate settings.
Of course whether the PS3 will then read the media you have may depend on the compatibility of the media files. You may just find it easier to play you tube direct to you PS3 from the internet?