Difference In Video Exposure Across Multiple Platforms

New to the forum, looking forward to hearing some feedback on this.

I'm editing my friend's wedding video, and have run into a problem regarding a specific sequence. They got married on the 4th of July, so they went outside and I have video of them in front of the fireworks. It's often just a silhouette, and when the in between fireworks the screen will go dark and you can no longer see their silhouette. Because of this, I was able to cut different fireworks sequences and put them together to make it look like one continuous sequence.

I uploaded the video 1080p to Vimeo, also exported the video to iTunes to share on Apple devices as 1080p. It looks great on my computer.

However, I was reviewing the video on different platforms and ran into a problem where the level of darkness is not the same as my laptop that I was editing the video on. During the firework sequence, their silhouette is visible the entire time, with a seemingly higher exposure than what it looks like in Final Cut, with the uploaded Vimeo video, and on the video in iTunes. Because their silhouette is exposed the entire time, you can easily see the cuts in between and it doesn't look very good, or at least what I was hoping to achieve with the edit.

I tried streaming the video on Apple TV on my television, viewed the video on Vimeo on a different laptop, also watched the quicktime file on the different laptop, and tried streaming the video on Vimeo on an iPad. All these platforms had the lighter exposure that displayed the cuts. But my computer shows the "higher quality" version that I was going for in Final Cut, iTunes, Quicktime, and Vimeo.

I have attached screen grabs of the two. Both screens are at full brightness, and they are both streaming the video on 1080p. The first picture in each sequence is from my computer, the darker one that I was hoping to go for.

I asked a friend of mine to watch, and she said she couldn't see sharp cuts while streaming on vimeo on her iPad. But of course, I don't know if she completely understands what I was asking her to check. If you would like to check out the video, I can be found at vimeo.com/kungfoolery

So essentially, what is causing the difference? How can I fix it so the exposure is correct on all platforms? I had already done some color correction, altered some of the exposure, etc. It looks perfect on my laptop, and even with compressed files that I exported.

Says file sizes were too big to attach. Here's a link to my flickr where I have uploaded the screen grabs.

www.flickr.com/photos/kungfoolery/sets/72157632884500194/

Use the scopes! There is now way to adjust black level or gamma unless you use scopes.

And scopes are easy to learn!

All computer screens and TV screen will handle color and gamma in slightly different ways. If you get your blacks touching, or slightly into the 0% line, and whites not quite touching the 100% line, you know it will never look better. What shows on various screens will be the best they can do.