Here is bad luck: most companies provide only a variety of content management systems via the Internet (the so-called Digital Signage systems). In fact, they pass screens control to the customers, in other words, to you. Even if it's the easiest of all the simplest control systems — it is extremely uncomfortable, hard, takes time, nerves, in general, these are just unnecessary worries.
Would you be able, for example, to choose the right software? Could you find and connect the necessary hardware? Will it be possible for you to edit/convert videos and pictures in the right format? And if it's not working - will you figure out why there is no picture, the video disappears, there is no sound, the wrong frequency, it's not switch on, not update, there is no internet, etc. And finally, can you plan and adjust the schedule for showing of about 500 videos?
We do not even ask about complex settings. For example, upload a logo above the video or connect social networks, etc.
And if you have nothing to show, do you need a control system then? And the last question: Do you really need this pain in the neck? You will get tired of contacting programmers with requests and complaints. And anyway, it's not their job. And you want a minimum of effort and maximum of pay-off..