Would you guys recommend buying an SSD to make up for weaker CPU? At least I read somewhere else that says a good SSD could make up for some speed with slightly slower CPU. I'm planning on buying a CPU around 110 dollar category from either company.
What's the better trade off? Sending less on CPU for an SSD, or spending more on CPU and use a traditional HHD?
Depends: are you worried more about storage or CPU performance? If it's either/or, a non-MMO gamer would probably be better off spending on the i5 than the SSD.
For the casual gamer, developer, web/email/docs user, the SSD will provide a benefit many times greater than the superior CPU.
For light loads, an i3 will be practically no different than an i5.
Video editing I don't do, but it seems to depend on the software. Non-linear work can apparently eat up storage IOs badly in some software, even with lots of RAM. OTOH, practically every non-FOSS video editor will make good use of faster and more CPUs, so...hard to say. If you're not sure, bring up task manager, then resource monitor, and check out your CPU, RAM, and disk IO loads, while doing some video editing. If you have CPU utilization dropouts at the same time as lots of HDD IO (or high wait time), an SSD would help that.
If you're waiting for applications to load, or ever-annoyed at the ticking and blinking away of the HDD, then you definitely want the SSD.