Yes, you can but it's quite complicated w/o keyboard. Takes time to use the remote. Won't recommend it. To watch web content (flash), I think you have to installed/download Adobe Flash Player or use HTML(???). Not really sure bout the technical things. I use this DVD player mostly to watch movies from Netflix/Amazon, which streams smoothly.
U can download mp4 files from youtube or other sites to the desktop of your mac or pc. Then insert a USB thumbdrive drag the mp4 files on the USB drive...then remove from your Mac or pc...open tiny door on front of Sony on right side...no words only USB icon. Stick in your USB thumbdrive. Turn on Sony, and hit menu and in the video section U see front usb...select with sony remote and a list of mp4 files shows up and select and play ... Sony also has menu of sites you get after you follow the complicated process of setting up the WIFI but most are pay or worthless.