Yeah, the battle mechanics of Ranged Attack are going to very, very important to get right. Tactics are everything now, because ranged attack is devastating, but the units doing the ranged attack could easily be wiped out by the right force if allowed to get close, i.e. fast-moving units.
At 45 seconds, there's a Ranged attack between Trebuchet and Pikeman. The Trebuchet has only a base 6 strength, but a Ranged Attack of 20. Interestingly, the Trebuchet has a lot of potential bonuses, i.e. 25% great general proximity, but they don't seem applicable to a ranged attack (but would presumably factor if attacked directly in melee combat).
The Pikeman have the 10 base strength but a strength of 0 against a ranged attack. And also we see that being in open Grassland is a -33% modifier! Wow.
The Trebuchet achieves a "Major Victory" and appears to do serious damage to the Pikeman... at least 50% killed, maybe more. But not totally wiped out, otherwise we'd see the "Total Victory."
Also, I don't see any combat odds... so I don't know if the battle is assured, or how the chances of victory work.
Secondly, there's a very interesting combat between two frigates @ 1:24. So, both Frigates are a base 30 strength and a 15 ranged attack. Instead of attacking, The player's Frigate (Roman, now) fires a ranged attack, taking roughly half the opposing Frigate's strength. He appears to have a few other Frigates to mop up. But the Ranged Attack now allows the opposing forces to not merely win, but to win without losses... which is a major change from Civ IV, where you had all or nothing attacks.
Also, on the Frigates, they have a ton of movement. The base is 5, but one appears to have gotten promotions up to 7 Movement. This would imply that you could come out of nowhere and launch an early ranged attack with a force of Frigates and do serious damage. The Pearl Harbor scenario would appear to be a very real possibility... and a player with a small navy could see it wiped out in a heartbeat, leaving the other side the impunity to "possibly" bombard coastal units and then skip back out to see.
*Note: we have no example of how sea vs. land ranged attack will work.
**Note: We also don't know if Navies will have Blitz attack, but I'm assuming they do not. Without armed transports, a convoy or land units could be entirely wiped out by one fast moving Frigate slipping in and destroying each and every one.
***Coastal bombardment will certainly be a factor, but still uncertain as to the mechanics. From JS:
"Ranged attacks in general play a major role in Civ V. All warships are now ranged units with the ability to hit land targets, dramatically increasing their importance relative to previous games in the series."