Good Morning Jeffsmiller
The Content Updates are updates that are available for content that is installed in Trainz (both built-in and downloaded). These updates generally repair content, or improve the content. We generally only recommend downloading updates for content that you use regularly, or are part of maps/sessions that you use regularly.
If an item is highlighted in red in the download window, then please place your cursor over the name of the item, and you should then see a message outlining why the download has failed. Please post this message, as it may help to track down the cause of the asset not downloading.
Regards
