Missing sound on online videos in IE 11

The sound issues minor in nature here are not from 10 so much but the 8.1 update for the sound card. One fast solution for online playback however would be trying the latest Firefox or Waterfox release if the 64bit Windows is in use and not the 32bit flavor of 10. You may want to check the IE Tools>Options>Advanced tab and scroll down to the bottom section to see if the Play sounds on web pages box is checked or not.

I would say IE11 itself is where the problem is from finding that box unchecked only after going to run a YT clip while remaining checked off at every other time you look. Personally while still seeing IE11 enabled on 10 I generally have given up on it entirely since it's earlier IE 9 and 10 versions became problematic and went for the 64bit Waterfox variant of FF being the first 64bit form seen.

Edge while still being a "work in progress" doesn't seem to have any problems while some embedded videos have been seeing the Adobe Flash Player allow/deny notification glued on top when in FF or Waterfox. Going from Insider Preview build to build I will occasionally run into a few minor bugs with the Windows assigned wav files for Sounds not playing back. The last two builds in particular have run into that while the general playback and even for gaming as well as media playback has been trouble free.

The main problem is not presently seeing enough 10 drivers available as each new version of Windows generally takes a full year to see most made available. So for sound here I went to the Creative support site and ended up using the 8.1 update's web updater in order to see actual 10 drivers download and install. But that wasn't anything browser related item.

Since you otherwise are not having any issues you know the correct drivers that work on already installed there and have to look at IE11 as not having been put on fully if the pc there didn't come with 10 already on and instead you had seen an upgrade take place. Upgrade installs can come out buggy in various ways at times.

Before 10 came along you used to be able to manually edit the System Registry in order to remove all entries for IE and see it removed entirely and then download IE separately to replace the buggy form of what comes in Windows with a fresh download. That hasn't been tried in 10 as far as I know with Edge now being the replacement MS is pushing and one reason why I have several browsers installed. If one suddenly goes buggy with a new release the next will be set as the default until one or more newer releases for the first are out.

That would tend to make a lot more sense if it should turn out to be a 3rd party culprit. You will need to test that idea a bit to confirm that it is however. Are those also running 10 as well?

IE has always been known to be flaky at times! This is one of the main reasons besides Tablet/Mobile mixed with Desktop OS is seeing MS move on dumping IE entirely for Edge which is a major overall while still being a major project in the works as far as infancy browsers go! It won't be ready for prime time while IE has always been around following the 9x family line up!