So, I'm a little confused by people saying RDM will have black/white magic since according to the slide they provided they've stated red magic is a hybrid of black and white magic... yet everyone is so focused on what healing spells RDM will get?

What we might be more likely to see are things like low oGCD abilities that help buff healing (think something like Mantra) and a buff/debuff to help DPS casters (similar to something like Foe's Requiem maybe?). I don't expect to see a piercing resistance debuff, though. If I remember correctly, there was an interview where Yoshi-P was asked if RDM would deal physical damage, and Yoshi-P started to explain but stopped himself because he didn't want to give anything away. If we do get one, then we're looking at DRG Disembowel being overwritten like with what happens to WAR Storm's Eye/NIN Dancing Edge and DRK Delirium/MNK Dragon Kick.

The skills used in the video to me ring of something like the MCH Wildfire. Cast "Chainspell" for X amount of seconds Y% of damage done to target is compiled and dealt at the end of the duration. Rushing in would allow the RDM to apply DoT(s) or a debuff, or get close to aide the party with a utility ability, and then jumping back out would re-position them to return to their red magic rotation. The positionals would be important because if you're too far from the main body of your party, they can't benefit from your utility, and if you're too close you're likely to eat more damage.

While the traditional RDM has been the jack of all trade, utilizing both white and black magic, it's been stated before that the FFXIV RDM would be different from previous installments (could be mis-remembering this and I don't remember when/where the statement was made). The hybridization of white/black could purely be lore related, and we will see the faintest of traces of white magic in the elements used for spells, or how a RDM might augment potency of party abilities/skills.

...Thoughts? Need someone to double check I'm not using crazy logic here.