It is by a hunter, Kripparrian: "I go over what to and what not to do in terms of global cooldown use, and cooldown stacking in this guide. Most of the info is general and directed at anyone playing WoW, not just hunters." It's a great video on general tips/tricks on casting, latency, cooldowns, mods, keybinds, and overall playing mentality, and can easily apply in many ways to tanking and healing as well.
Healing is a bit more reactionary than dps is, since it is (in most cases) difficult to predict damage incoming on the tank (sans notable boss abilities being cast at them, like Frozen Slash or Meteor Fists), but I think that most druid healers can empathize with a more proactive casting. Boss mods will assist greatly in timing these abilities (which is why I have my DBM bars finish right next to my grid frames). We aren't able to "save" our big heals for when our trinkets happen to proc or a synergistic cooldown is available since the tank can die in that time, but the basic idea is certainly there. We still have to worry about being able to heal (or cast) on the run, watch our cooldowns, spam keys, and have easy-access keybinds (which can include Clique) to cut down time between spell casts.
Tanking is more in-line with DPS in regards to its ability to spam and stack attacks for threat generation, but they will need to also weave in shielding/mitigation cooldowns in accordance with the boss' own timed attacks, healer mana, and overall heals incoming on themselves (especially if healers die). Again, boss mods will assist greatly in timing these larger damage spikes.
FYI, a good macro for combining cooldowns into one key along with a spellcast is such:
Most cooldowns are able to be chained like this, as they do not proc the GCD by themselves. Replace Cooldown1, Cooldown2, and Spellname with chosen spells. Trinkets can be used in place of cooldowns. If you'd prefer not to write out trinket names, you can instead type /use 13 and /use 14 in place of the /cast Cooldown, where the 13 and 14 refer to the slots on your character window for your trinkets.
You can insert modifier keys to make it more variable, such as:
|/cast [mod:shift]  Cooldown1|
/cast [mod:shift] Cooldown2
/cast [mod:shift] Spellname1; Spellname2
...which would cast, if shift is held, both cooldowns and spellname1, or if shift is not held, cast cooldown1 and spellname2.
One thing that he didn't cover, however, was selecting targets during trash pulls. The faster you can select the right target (being the one the tank is building threat on), the faster you can get damage pouring into the mob without pulling aggro. MT frames or, even more quickly, a focus-target assist (where the tank is your focus target) can aid in selecting the correct target; tanks that use raid-marking macros can also speed up your target selection by putting an icon on the mob.
Applause to Kripparrian on a well thought-out video tutorial!