Hi Alan, welcome to the forums. I'm not sure what is causing the error you're seeing when attempting to view the calendar on icalx. Another host you could try would be
http://www.ical-mac.com. Also, the
FAQ provides instructions that may help get you started.
Regarding the ability to show images or videos within the calendar (or popup reminder window), this won't be possible when viewing the calendar online. These capabilities are only present in VueMinder Calendar Pro when viewing the event description or receiving popup reminders. Also, to clarify, videos can't appear within the event description, those only appear in the popup reminder window. VueMinder publishes calendars using the iCalendar file standard, which unfortunately doesn't support these types of extensions. The data is included in the published file, but other web calendars don't know how to process the data since it's not part of the standard.
However, if you host your pictures or videos online, and other people use VueMinder Calendar to subscribe to your published calenndar file, then they'll also be able to see whichever pictures or videos you specify. The event editor assumes local files will be used for showing pictures and videos, but you can specify the web URL to your files and it will work (I think - I've only tested this for pictures, not videos).
I hope that helps. Please let me know if you have any other questions.