Thanks for the reply but perhaps I did not make it clear enough that the file I want to play is on my sd card within the tablet, not on a website. This is what I meant by playing content 'off-line'.
Rolling back updates is not an option because that installation of Opera was uninstalled when it stopped working. (Stupidly on my part, maybe.)
The content is an interactive tour such as this
http://dld.bz/millsandbloom Please do not assume that I would know how to 'roll back updates' or 'change to desktop mode' without instruction. I do really appreciate your help with this. Just please assume you are talking to an idiot who needs step by step instruction.