Some users have experienced issues with uploading Mario Kart 8 highlights to YouTube, so Nintendo is working on a fix.
Part of the appeal of building replays in the Wii U racer is the ability for fans to upload content directly from the game into a linked YouTube account, bypassing the need to hook up the console to a dedicated recording device. With the most recent update for the game, some users have reported an error code 104-1852 during the upload, with the video failing as a result.
An update from Nintendo has confirmed that they are aware and will issue a system update as a fix shortly.
Have you uploaded your highlights to YouTube? If so, do share!