David is having issues with contact duplications across multiple contact lists due to sync. What can he do to clean them up? Leo says to pick one contact list to clean up. You can use apps to find duplicates and merge them into a single contact. It'll take some time. Though Leo doesn't advise deleting old ones, in case you need to contact them someday. Once you've eliminated the dupes. SAVE IT. Back it up. It's your "canonical address book."
Then go to other address book locations and delete them all. Once you've done that, you can import your Canonical address Book. And turn syncing back on. Now you've cleaned up all your address books. But this isn't something you can only do once. You'll have to do it again from time to time because sync creates duplicates.
Dave also wants to know what format he should record his college video lectures on. He's recording in .mov. How can he save it into a smaller codec? Leo says you can use iMovie, and Leo advises recording in H.265 / HEVC. Most modern codecs are a combination of high compression, but good quality. Leo used to use ScreenFlow. He also likes Camtasia.
Leo also suggests reencoding your lectures using Handbrake.fr.Or just upload it to YouTube and let them do all the heavy lifting, encoding in more than 40 different formats. Just upload your best quality video and they will do the rest.
Check out Alex Lindsay's Office Hours for other suggestions.