We had to remove «Saving with original names» from BGram for stability reasons.
Actually this feature wasn't saving media to storage. In fact, it just changes the title of the media downloaded to cache folder. Some features like theming and bots downloading files, require telegram generated random names to work reliable, so the problems caused by this function:
1) new backgrounds do not work;
2) photos do not open as files;
3) gifs and video do not work properly;
4) fewer files with the original name are saved after 4.6;
5) favorite stickers work incorrectly.
To save file with its true name download file, then use «Save to downloads» or «Save to chat folder» in message context menu.
Take notice: it is relevant for all Telegram clients, including Plus, Mobo, etc.