Just when you think a particular video format has become the norm, then somebody goes and creates a new one, better, faster more compact etc.
Or your favourite video clip has been recorded in some proprietary format. Whatever the reason, somebody somewhere wants to convert one format to another. This is by no means a definitive list, but here are some converters which have been used and reviewed.
Can you open a PDF in Office - No!!!
What do you mean you can not edit a PDF document in Office, this certainly used to be the case! The only way SoSLUG previously found to edit a PDF file and belive you me we looked, you first needed to import any PDF into "Inkscape" and convert, whilst you can edit the file and alter it you needed to save the file either as an "Inkscape" drawing or save back to a PDF by exporting. Whilst there is little problem with this if you needed to continually edit the file it can be a bit of a pain.