Any physical assembly used to process video software.
Video Hardware is any hardware used to create produce edit render moving graphics or video by itself or in conjunction with other hardware.

Video hardware, a hacked Atari video cable with added line red spl…—blakespot (Flickr.com)
The first piece of video hardware is your computer, and all of its hardware components which enable the computer to create edit, and render/produce videos that can be transmitted to a viewing screen. What constitutes the wide array of Video Hardware is any hardware used to create produce edit render moving graphics or video by itself or in conjunction with other hardware in a system and or subsystem. In short any hardware used or involved in video production.
My personal computer was built with only one thing in mind and that one thing was VIDEO.
The Video Hardware in my system starts with my motherboard which is an Asus SABERTOOTH X-58, next I have an Intel Golftown Extreme Edition Six Core I7 980 Processor that is over clocked, My Memory is 24 GBytes of Triple Channel DDR3 Ram, and my storage is C: Drive SSD Corsair Force 3 SSD ATA D: Drive SATA E: Drive SATA, the full size ATA case is Corsair as is my power supply; the DVD-ROM is LG, the main video monitor is a 22 inch LG FLATRON E2241, the second video monitor is a 19” Viewsonic VG710b, the webcam is a 5.0 Million Pixel Rocksoul wc-103webcam being upgraded to a Logitech C920 HD Pro Webcam, the heart of my Video Hardware is a dedicated ATI Radeon HD 5870 GDDR5 1024 Mbytes Graphics Card.
The hardware that you use may be different but most likely with a little bit of patience you could probably render video in 720P HD quality video perfect for use on the video hosting sites on the internet, you know the ones like YouTube, Vimeo, Metacafe, Dailymotion, Flicr, Facebook etc
Video Hardware includes very specialized professional Video Graphics Cards for video capture, video streaming, etc.
Video Hardware can be assembled in dedicated video networked systems with specialized individual workstations each workstation equipped for processing different aspects of editing inserting special effects and or rendering video and audio to create and complete professional video productions.
On the higher end of the spectrum
there are dedicated workstations for use with highly specialized video/graphics software such as the high end of Adobe Creative Cloud with Photoshop, Lightroom, Premiere Pro, Illustrator, In Design, After Effects, Audition, Dreamweaver, Muse, Flash Professional, Edge Reflow. Then there are workstations designed to work with Sony Vegas Pro. Other specialized Video Hardware is also assembled in systems, networks and work stations for software such as Final Cut Pro, Media Composer, Magix Video Pro, Edius Pro, Lightworks, HitFilm, NewTek etc. Mobile-EDIT Laptop Notebooks for video are also included in Video Hardware as well.
Video is only as good as the audio.
Therefore the microphone, cabling, mixer, editing deck, integrated or dedicated sound cards are all part of the Video Hardware. For example I use multiple microphones such as my Turtle Beach wireless headset, my shure brothers M68A mixer where I use either my Sennheiser 838 cardioid pattern dynamic hand held , or my Audix OM2 dynamic hand held corded microphones connected to coaxial cable fitted with Shure XLR fittings. The microphones are mounted to a shure brothers professional microphone stand.
I am really considering adding a Hero Pro video camera shortly, isn’t technology great?
No matter what Video Hardware you have or use it is a mute point or useless without you, you are the heart of your videos.
In the end your videos will only be as good as you regardless of the hardware you use. Have fun with videography after all isn’t that what it’s all about.
-Bruce