FFMPEG errors after installing plugin through Homebridge UI
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**Describe The Problem:**
Originally referenced here: https://github.com/hjdhjd/homebridge-unifi-protect/issues/422

I realized that I did not explicitly state how I installed the application (this might be good information to include in the template or if it's there sorry I missed it!). I did install the application through the HomeBridge UI by simply searching for and installing the plugin and setting the NVR settings.

Because I was not clear on how I installed the application, it was incorrectly assumed I installed the application through an improper means and the fix suggestion was simply uninstall and install the application correctly. I uninstalled, and followed the same installation process as I did the first time, which was the process recommended by the author. 

The result is the same however, but I had no means to re-open the ticket. I'm not sure what the next troubleshooting step might be but the issue persists.

**To Reproduce:**
Access any camera directly either by clicking on the tile for any Unifi camera or by clicking on an alert (such as the doorbell ringing).

**Logs:**
Note: I removed the MAC Addresses

```
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4]: Connected to the Protect controller API (address: 10.10.10.166 mac:).
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4]: Connected to the UniFi realtime update events API.
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4]: Discovered camera: Driveway [UVC G4 Pro] (address: 10.10.10.92 mac:).
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4]: Discovered camera: Backyard [UVC G4 Pro] (address: 10.10.10.10 mac:).
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4]: Discovered camera: Side stairs [UVC G4 Pro] (address: 10.10.10.86 mac:).
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4]: Discovered camera: Garage [UVC G3 Flex] (address: 10.10.10.106 mac:).
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4]: Discovered camera: Doorbell [UVC G4 Doorbell] (address: 10.10.10.183 mac:).
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4]: Controller refresh interval set to 10 seconds.
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4] Doorbell [UVC G4 Doorbell]: Discovered doorbell message switch: LEAVE PACKAGE AT DOOR.
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4] Doorbell [UVC G4 Doorbell]: Discovered doorbell message switch: DO NOT DISTURB.
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4] Doorbell [UVC G4 Doorbell]: Discovered doorbell message switch: PRESS TO SUMMON DOG..
[6/12/2021, 12:53:28 PM] [UniFi Protect] UNVR [UNVR4] Doorbell [UVC G4 Doorbell]: Doorbell message set: PRESS TO SUMMON DOG..

node:99976) UnhandledPromiseRejectionWarning: Error: Command failed with ENOENT: ffmpeg -codecs
spawn ffmpeg ENOENT
at Process.ChildProcess._handle.onexit (internal/child_process.js:267:19)
at onErrorNT (internal/child_process.js:469:16)
at processTicksAndRejections (internal/process/task_queues.js:84:21)
(node:99976) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag --unhandled-rejections=strict (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)
(node:99976) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
```

**Homebridge Configuration:**

```json
{
    "controllers": [
        {
            "address": "10.10.10.166",
            "password": "<hidden>",
            "username": "homebridge"
        }
    ],
    "platform": "UniFi Protect"
}.
```

**Screenshots:**
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**Environment:**

* **Homebridge Version:**  1.3.4
* **Node Version:** 12.18.4
* **Homebridge-UniFi-Protect Plugin Version:** 4.4.0
* **UniFi Protect Version:** 1.18.1
* **UniFi Protect Controller Type:** UNVR
* **UniFi Protect Controller Firmware Version:** 1.4.9
* **Apple Device and iOS / macOS / iPadOS / tvOS Version:** <iOS 14.6 (iPhone & iPAD) & MacOS 11.4
* **Operating System and OS Version:** MacOS 10.3.16

**Note:**
My HomeBridge host is a Mac mini (late 2012) with 16gb of ram, 2.5ghz i5 and Intel HD Graphics 4000. It's running macOS High Sierra (nervous about updating it because of its age and what it may or may not do to HomeBridge).

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