filming objects that emit light in low light conditions
This type of photography is called 'available light' which covers shooting subjects without adding strobes or other lights. It is favored by many photographers for many reasons. I personally favor this because the subject and scene appear more natural to me. Things that glow interest me as well and there are tons of things that fit this: the moon, neon art, neon signs, street light reflections on the surface of wet pavement, faces illuminated by camp fire, Christmas lights and decorations, just to name a few.

Each of these subjects will require the photographer to make needed adjustments to capture the light. Let's start with the brightest thing in my list, the moon. The moon as you know does not emit light, but rather reflects the light from the sun. As I recall when I would measure it with my digital spot meter, a full moon might be close to or exceed 12 EV. When I shoot video of the moon where it is almost 50% of the frame, I have found these things that assist:

1) very high magnification, 80x to 100x

2) heavy tripod and no vibration

3) do not touch camera while recording, use remote to start and stop

4) manual exposure

5) manual focus

6) set the white balance to outdoor (sunlight)

7) setting up these things before starting the recording.

According to the specs on the Canon HF100 it has both manual exposure and manual focus.
When I put my Sony in digital zoom, I notice that the manual focus is not always accurate as far as the numbers go, so I trick it by first lining up the moon in the middle of the frame, set focus to auto then after it adjusts, I lock it down by pressing the manual button. I adjust the manual exposure by looking at how much detail I want on the surface.

example of moon shot:

https://vimeo.com/11145790

Notes: in the example the motion is sped up 4x in post production, also note the wavy lines as per atmospheric distortion.

Regarding the issue you are having with "the camera is that it quickly renders the objects to be white when in fact they emit purple light (the diffuser is purple on the object)."

This could be more than just one thing that needs adjustment. First I would check that you are not over exposing the lamp, then I would also make sure you have set the proper white balance as well. If you were expecting to capture both the purple lamp and an illuminated face, the lamp may be too bright for this or that the dynamic range of getting the lamp's purple glow and enough illumination to see detail on your subject's face may exceed the camera's dynamic range. You may have to change the bulb in the light to be brighter or darker to bring it in range.

Also note that in very low light situations, less than 10 LUX, you may start to notice digital noise in the black areas.

Shooting a light emitting object in sunlight is going to be difficult as you are correct in thinking that the daylight is too intense compared to your subject. Remember the sun is so bright that it may harm your sensor if you expose the sun directly for extended periods of time.

Another thing you can do is add a reflector on your subject as a fill light or add highlight. Here is an example:


                
            

Balancing the light of a scene will take some practice and some experimentation. Let's say you wanted to shoot a scene outside in daylight and your subject is working on a laptop. Your goal is to have the subject's features to be illuminated and at the same time be able to read or see detail on the laptop screen. To do this, you will likely have to shoot these in the shade to reduce the amount of daylight in your frame, and may have to use a reflector on your subject as well as put the laptop display in max brightness. It's all a balancing act of light.

If you can not afford a light meter, or spot meter, use your camera's display as the best source of how the scene will be balanced for light.

I recommend that you examine your display carefully to see that all the things you want are properly illuminated. Some scenes may have extreme high and low values of light that exceed the dynamic range of your camera.

Summary:
Capturing things that reflect light or emit light can be interesting yet require camera adjustments and good planning. Adjustments include: manual exposure, manual focus, manual white balance, possibly using a reflector, and if possible change the brightness of any lamps in your scene.