I'd taken a break from reading other people's blogs, but when I had a look to see what I'd been missing I found a superb 4-part essay by Peter Leithart on the subject of paedocommunion - the admission of baptised children to the Lord's Table.
Apple no longer supports its QuickTime player. Both the player and the browser plugins were found to have security flaws which meant a malicious website could trick you to playing a doctored file in the player / plugin, which would then allow those vulnerabilities to be exploited.
The answer is simple: Install another player. Like VideoLan's VLC Player.