Anything can be risky on a computer depending on skillset/computer awareness and familiarity. I don't particularly find a problem with codec-packs that are designed allow you to enable disable particular individual codecs within the pack, especially for one-off purposes. These systems are designed not to interfere with existing codecs - they do not override existing codec merit unless you want it to. Certainly, some people can abuse them, and some may be overconfident of their abilities.
A lot of folks coming to video from music and audio may have perceptions about how video should perform within an application. One thing to note is that you are
not a video editor, and are not responsible for the video and its audio, only for providing a music soundtrack. Generally, you provide a synced music track, and the video editor adds that to his video project. You, the composer, only need video is as a reference for your score. This means you should be able to take the provided reference video and create a low resolution dub of it for yourself that is more suitable for use within an audio application. Using HD video within a DAW is simply wasting available CPU resources that will not be available to the DAW for audio use. It makes much more sense to create a low resolution dub for scoring duty.
Sometimes, clients may ask for you to create a video with the music track embedded. This should be considered as a minor duty and for the client's
reference only. A low resolution copy similar to what was used for scoring should be appropriate. You aren't being paid as a audio mixer for video, it's not your responsibility, but there's no harm in giving your interpretation.
If the client is asking you for a high definition copy with the intention to use it for final distribution - you have moved beyond scoring and into audio (for video) production. This is beyond the scoring bailiwick - but it is an opportunity to make more money. However, it does mean that you should then transfer your rendered music track to a
proper Video Editor system along with the client supplied video. The DAW is not the place to create finalized video. Learning more about video editing is useful skill set .