I see that there is a Begoniax loading screen, I can't remember seeing it in the PC version, so I suppose it was something that was included for the HD remake?
The said Bégoniax loading screen actually originates from the original Xbox version. For some reasons in that version they used this loading screen with Bégoniax, the loading bar and a text above the latter that says "Loading...", instead of using the loading screens that have all the other characters and hoodlums like in every other version.
Here's the Bégoniax loading screen from the original Xbox version:
It's also worth to mention that the "vignette" folder (in which the loading screens for Rayman 3 are usually stored) of the original Xbox version contains 5 variants of this loading screen; one for each main (european) language of the game (english, french, german, italian and spanish), that change the "Loading..." text in "Chargement...", "Lade...", "Caricamento..." and "Cargando..." respectively, plus 5 folders that only contains the menu texture, again, one for each main language of the game.
Now, for both HD versions (PS3 and Xbox 360) they took the "vignette" folder directly from the original Xbox version and putted it in the game files, but there are quite some weird changes. The first one being that other than the Bégoniax loading screen and the folders for the menu texture, they also included the "Ubisoft Entertainment" splash screen and the "Usual suspects. Rayman 3" unused splash screen, both from the "vignette" folder from the PC version, plus the "FRANCIS" folder, which contains all the unused story text screens (also took from the PC version), with the additions of the HD versions game icon and exclusive loading screen.
The second weirder thing is that the Bégoniax loading screens got upascaled to be more in line with the other textures for the HD versions, while every other content in the "vignette" folder didn't got upscaled.
Here's the Bégoniax loading screen from the HD versions:
They made it widescreen by cutting the upper part, and also changed the loading bar and the text styles to have outlines and stick out more, but the proportions for the said elements are exactly the same as the Bégoniax loading screen from the original Xbox version.
Judging by the quality of the mage, it doesn't even look like it goot upscaled, but rather remade entierly with all the assets, including the Bégoniax screen, which they have probably redone by using an higher quality render of the same model. Same goes for the background.
But the even weirder thing is that they also included a bad upscale attempt of the Bégoniax loading screen in the same folder (only for the english one), which is this one:
More than just bad upscaled, it seems more like color compressed, but the image quality is also worse, so I don't know; it could be both (Hakyra could tell it better than me, surely).
For completition purpose, I also have to specify the names and formats of the images in the "vignette" folder.
The Bégoniax loading screen of the original Xbox version is just called "Rayman3", but since this is also the name of the "Usual suspects. Rayman 3" unused splash screen, and since they're both in the same folder in the HD versions, it got renamed in "Rayman3_eng" in the "vignette" folder of the HD versions, making it more in line with the Bégoniax loading screen of the other main languages of the game, which are called "Rayman3_fr", "Rayman3_ge", "Rayman3_it" and "Rayman3_es" respectively.
Both the good quality and the bad quality english Bégoniax loading screens are put in the same folder because the loading screens are usually in BMP format, but the bad quality one is in DDS format, which is also the format for the Xbox menu texture and most of the assets of the HD versions exclusive loading screen, except there is also a BMP version of the main image for the said loading screen. I don't know what are the properties and advantages of both formats, so I don't know why they did this; I'm only reporting how the textures are stored in the game files.
It goes without saying, but the Bégoniax loading screens are unused in the HD versions. Perhaps they upscaled/remade them to be used, but at last they didn't. You may wonder why they would ever want to use the original Xbox version loading screen? Well, because the HD versions are built on top of the original Xbox version as a base. You can notice this by looking at some small deteils, like the fact that it says "Please Press START to begin" in the title screen; only the original Xbox version says this, while the other versions say "Press START" or "Press START to begin", but only the original Xbox version adds the "Please" in the phrase. Another deteil is the smoke that comes from rightest torch near the Leptys statue in DotK secton 2; the smoke it's broken, and it's also brighter than in the other versions. Lastly, the illumination colors are generally closer to the original Xbox ones.
I haven't checked the Xbox 360 prototype myself, so I don't know if there are all the Bégoniax loading screens I listed above, but either way, I gave quite a deteiled explenation about it.