I own open canvas version 4+, but it only produces OE4 event files, While I often find posts with WPE files including a link to a very early version of OC. I doubt that they will play newer version files.
As it is now I have a link for the (few) visitors of my webpage to download the entire trial version of OC4 to view my event files. Which seems like overkill.
Isn't there an external viewer in existence?