Recursively move subtitle files into subdirectories

find . -name 'Subtitles' -prune -o -type f -name '*.srt' -printf '%h\0' | sort -zu | while IFS= read -d '' -r d; do
    printf "Creating '%s'...\n" "${d}/Subtitles"
    printf "Moving '%s' to '%s'...\n" "${d}/*.srt" "${d}/Subtitles"
done

Will find the path of every .srt file in the current working directory, recursively, excluding those contained in a directory named "Subtitles", printing only their basename and filtering out duplicates, creating a "Subtitles" directory inside each resulting path (if not existing) and moving every .srt file at its level inside it.

It will deal with .srt files located at any depth of the current working directory, and so with the "TV Shows" directory as well.

The command will perform a dry run; if the output looks good, run the actual command:

find . -name 'Subtitles' -prune -o -type f -name '*.srt' -printf '%h\0' | sort -zu | while IFS= read -d '' -r d; do
    mkdir -p "${d}/Subtitles"
    mv "${d}"/*.srt "${d}/Subtitles"
done

% tree -a
.
├── foo
│   └── bar
│       ├── baz
│       │   └── Subtitles
│       │       └── sub_baz.srt
│       └── sub_bar.srt
└── sub.srt

5 directories, 3 files
% find . -name 'Subtitles' -prune -o -type f -name '*.srt' -printf '%h\0' | sort -zu | while IFS= read -d '' -r d; do
    mkdir -p "${d}/Subtitles"
    mv "${d}"/*.srt "${d}/Subtitles"
done
% tree -a
.
├── foo
│   └── bar
│       ├── baz
│       │   └── Subtitles
│       │       └── sub_baz.srt
│       └── Subtitles
│           └── sub_bar.srt
└── Subtitles
    └── sub.srt

7 directories, 3 files

Here's another approach. Use bash's globstar option to allow for recursing into subdirectories. From man bash:

globstar

If set, the pattern ** used in a pathname expansion context will match all files and zero or more directories and subdirectories. If the pattern is followed by a /, only directories and subdirectories match.

So **/ will only match directories, but it will include sub-directories. With this in mind, you can do:

shopt -s globstar
for d in **/; do mkdir -p "$d/Subtitles" && mv "$d/"*.srt "$d"/Subtitles ; done
rmdir **/Subtitles/

I tested it using this set of files and directories:

$ tree
.
├── a
├── b
├── Movies
│   └── Avatar
│       ├── Avatar (2009).de.sdh.forced.srt
│       ├── Avatar (2009).de.srt
│       ├── Avatar (2009).en.forced.ass
│       ├── Avatar (2009).eng.srt
│       ├── Avatar (2009).en.sdh.srt
│       └── Avatar (2009).mkv
└── TV Shows
    └── Game Of Thrones
        └── Season 02
            ├── Game Of Thrones - s02e03.emg.srt
            ├── Game Of Thrones - s02e03.en.forced.srt
            └── Game Of Thrones - s02e03.mp4

6 directories, 11 files

After running the command above, I ended up with:

$ tree
.
├── a
├── b
├── Movies
│   └── Avatar
│       ├── Avatar (2009).en.forced.ass
│       ├── Avatar (2009).mkv
│       └── Subtitles
│           ├── Avatar (2009).de.sdh.forced.srt
│           ├── Avatar (2009).de.srt
│           ├── Avatar (2009).eng.srt
│           └── Avatar (2009).en.sdh.srt
└── TV Shows
    └── Game Of Thrones
        └── Season 02
            ├── Game Of Thrones - s02e03.mp4
            └── Subtitles
                ├── Game Of Thrones - s02e03.emg.srt
                └── Game Of Thrones - s02e03.en.forced.srt

8 directories, 11 files

Note that it will throw out some warnings for cases where there are no srt files in a directory since it will then try to run mv directory_name/*srt directory_name/Subtitles but since the *.srt glob matches nothing, it will return itself (unless you have the nullglob option activated), and as there is no file whose name is literally *srt, it will fail. This is also why I had to add rmdir **/Subtitles to remove empty Subtitles directories. You can safely add 2> /dev/null to the end of the mv command to hide these warnings.

Alternatively, you can do something slightly more complex and only create the dir and try to copy when you know you have *.srt files:

shopt -s globstar
shopt -s nullglob
for d in **/; do 
  subs=( "$d"/*.srt ) 
  [[ ${#subs[@]} -gt 0 ]] && 
    mkdir -p "$d"/Subtitles && 
      mv "$d"/*srt "$d"/Subtitles
done

Which results in the desired output in a single pass. To avoid moving files if they are already in a Subtitles directory, use the extglob bash option that lets you build more complex globs, and just look for any directory whose name is not Subtitles:

shopt -s globstar nullglob extglob
for d in **/!(Subtitles)/; do 
  subs=( "$d"/*.srt ) 
  [[ ${#subs[@]} -gt 0 ]] && 
    mkdir -p "$d"/Subtitles && 
      mv "$d"/*srt "$d"/Subtitles
done