I/O is the transfer rate between the hard disk and ram. All computers, servers and mobile devices have a maximum I/O the max is determined by the cpu speed, bus speed, hard drives and ram. All shared hosts, clouds and virtual private server use some form soft I/O limit or cap to ensure that you do not effect other users on the same server.
When sharing a video online on a shared server you need to know your the I/O of your hosting and bitrate of video. Using the two you can work out the maxium users that can use your site at one time without getting in trouble with your web host. For example if your video is 1080p x264 at 4000 Kbps then that is 400kb/sec which means... 10 users watching your video would be 4000kb/sec which is your limit of the I/O.
Shared hosting is a not a platform that is recommended for video hosting due to the fact of the I/O and bandwidth restrictions these shared hosting companies enforce. This is why so many companies use YouTube and other streaming services because its cheaper to do so.
Most shared hosting platforms will have thousands to hundreds of thousands of customers on the same server, each will be allocated a % of the max I/O transfer or have terms and conditions not to constantly use too much. In your case you have exceeded your maximum I/O write allocated to you and therefore have landed yourself a suspension for breaking the terms of service.
But... Wait... What About Unlimited Hosting
Sadly many people believe they have unlimited hosting when in fact they do not. Unlimited hosting is according to their acceptable usage policy. Shared hosting is never unlimited and its kinda false advertising but they have been getting away with it for decades.
Virtual Private Servers, Dedicated Servers, Content Delivery Networks and Cloud Servers
VPS, Dedicated Servers, CDN, Cloud servers will have a higher I/O limit because they generally use better technologies, less user contention and a higher array of disks. If you can afford better hosting then you will need to use something like this or use YouTube.