What kind of vocal compression is Christina Grimmie using to get this sound for her voice?

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Good luck!

It's not just the compression. If you compress that vocal track you'll just get more of the unfortunate room sound.

What did you expect recording her with the mic so far away and facing a brick wall?

Step 1. Get a great room sound by getting a great room. You look like you're on the back porch.

Step 2. Position the mic so that the sound is sweet and fat. This is trial and error. The sound is more imporatant than the look. Make sure that the mic is set to cardiod, unless the room sounds unbelievably great, in which case omni might maybe work. But probably not.

Step 3. Repeat step 2 til it's great.

Step 4. Almost any compressor will now be fine. Don't set it too fast. The Logic compressor is OK if a bit colourless. I love the UAD Fairchild emulation. Waves do some great vintage emulations as well. Vintage emulations add a bit of je ne sais quoi (AKA distortion) that sounds sweet.

Step 5. Get her to bleed for the song as she sings it. Anything less won't make an impact out there. There are many millions of OK singers.

Step 6. Be curious. Try things out. Who knows. You may hit on something unique!

Cheers

It's more a combination of reverb, Eq & compression - reverb especially (large ballad style hall or plate). The Christina Grimmie video has had some mixing/ post production - you can hear when she's talking in the intro, the voice sounds very different to her performance, (suggesting that the audio was recorded separately into Logic, then synced to picture).

I'm assuming you're recording video & audio direct to your camcorder (via the Focusrite) - you could try experimenting with some of the channelstrip performance presets (like "Female ambient lead vocal"), though you'll need to tweak. A better solution would be to record the piano to one stereo track, vocal to another mono track, then spend time mixing, & finally syncing to video. It sounds like you're monitoring the piano from it's in built speakers (though I could be wrong) - I'd recommend using it's outputs, so that the mic doesn't pick it up.

A few other recording tips : I'd move Madi & the piano a little further away from that wall, & possibly hang a nice rug behind to reduce the boxiness. I'd also move the mic a little closer to get a more intimate sound. Lastly, make sure Madi is singing straingt into the mic - it looks a little off axis which can seriously change the tonality. As a rule, you can't go far wrong if you're singing straight at the logo on most cardiod mics. A small pop shield or windshield would also help with sibilance (which is even quite prominent in Christina's performance).

Best of luck!